02 Chep Thermodynamics and Thermochemisty Ques. Final E
Short Description
thermo...
Description
Thermodynamics and Thermochemistry Thermochemistry 158 Thermodynamics 18. 9.
10.
Heat produced in calories by the combustion of one gram of carbon is called (a) Heat of combusti combustion on of carbo carbon n (b) Heat of formatio formation n of carbon carbon (c) Caloric Caloric value value of of carbon carbon (d) Heat of of producti production on of carbon carbon Conditions of standard state used in thermochemistry is (a) 0o C an and 1 atm
(b) 20o C and 1 atm
(c) 25o C an and 1 atm (d) 0 K and 1 atm 11. The temperature temperature of the the system decreases decreases in an (a) diabatic co compression (b) !sothermal compression (c) !sotherm !sothermal al e"pans e"pansion(d) ion(d) diabatic diabatic e"pans e"pansion ion 12. #or the isothermal e"pansion of an ideal gas (a) $ and H incr increas eases es (b) $ increase increases s but H decrease decreases s (c) H increase increases s but $ decre decreases ases (d) $ and H are are unalte unaltered red 13. !f a refrigerator%s door is opened& then 'e get (a) oom heate heated d (b) oom cooled cooled (c) ore ore amount amount of heat heat is passed passed out out (d) *o e+e e+ect ct on room room 14. The cooling in refrigerator refrigerator is due to (a) eactio eaction n of the refriger refrigerator ator gas
(a) $ual $ual to the heat heat absorbed absorbed (b) $ual $ual to the heat heat evolved evolved (c) $ual $ual to to the 'or, 'or, done done (d) (d) $ua $uall to the sum of the heat heat abso absorb rbed ed and 'or, done 19. !t is gene genera rall prin princi cipl ple e that that the the less less ener energy gy a system contains& it is (a) ess stable (b) ore stable (c) nstable (d) ore unstable 20. !nternal energy is an e"ample of (a) -ath fu function (b) 3tate fu function (c) 4oth (a) and (b) (d) *one of these 21. The process& in 'hich no heat enters enters or leaves the system& is termed as (a) !sochoric (b) !sobaric (c) !sothermal (d) diabatic 22. The intensive intensive property property among these these uantities uantities is (a (a) $nthalpy (b) assvolume (c) a ass (d) 6olume 23. !n thermodynamics 'hich one of the follo'ing is not an intensive property (a) -ressure (b) 7ensity (c) 6olume (d) Temperature 24. !f in a cont contai aine nerr neit neithe herr mass mass and and nor nor heat heat e"change occurs then it constitutes a (a) Closed system (b) 8pen system (c) !solated sy system (d) !maginary sy system 25. .hich of the follo'ing is not a state function (a) ∆S (b) ∆G
(b) (b) $"pa $"pans nsio ion n of ice ice (c) The e"pans e"pansion ion of the gas in the refrige refrigerator rator (d) The 'or, 'or, of the the compres compressor sor 15. -oint oint out out the the 'ron 'rong g stat statem emen entt in rela relati tion on to enthalpy (a) !t is a state state funct function ion (b) !t is an intens intensive ive proper property ty (c) !t is indep indepen ende dent nt of the path path follo' follo'ed ed for the change (d) !ts !ts value alue depends upon the amou mount of substance in the system 16. .hich .hich of the follo'in follo'ing g is /ero /ero for an isoch isochori oric c process (a) dP (c) dT 17.
dV (d) dE
(b)
!n an isochoric isochoric process process the increase increase in interna internall energy is
26.
27.
28.
(c) ∆H (d) ∆Q .hich .hich of the follo'in follo'ing g is true true for an adiaba adiabatic tic process (a) ∆H = 0 (b) ∆W = 0 (c) ∆Q = 0 (d) ∆V = 0 .hich of the follo'ing is not a state function (a) ! nt nternal energy (b) $nthalpy (c) .o .or, (d) $ntropy mong them intensive property is (a) ass (b) 6olume (c) 3urface tension (d) $nthalpy
First law of thermodynamics thermodynamics and Hess law l aw 1.
The rst la' of thermodynamics thermodynamics is only (a) The la' of of conservati conservation on of energy energy
ar, the correct statement statement
(b) The la' la' of conserv conservation ation of mass mass
(a) #or a chemi chemical cal react reaction ion to be feasib feasible le&& ∆G should be /ero (b) $ntropy is a measure measure of order in a system
(c) The la' la' of conserv conservation ation of momen momentum tum
(c) #or a chemi chemical cal react reaction ion to be feasibl feasible& e& ∆G should be positive (d) (d) The The tota totall energ nergy y of an isol isolat ated ed syst system em is constant
(d) 4oth 4oth (a) (a) and and (b) (b) 2.
mi"ture of t'o moles of carbon mono"ide and one mole of o"ygen& in a closed vessel is ignited to convert the carbon mono"ide to carbon dio"ide9 !f enthalp lpy y chan change ge and ∆E is the the ∆H is the entha change in internal energy& then
Thermodynamics and Thermochemistry Thermochemistry 159 Thermodynamics
(a)
∆H > ∆E
(b)
∆H < ∆E
(c)
∆H = ∆E
(b) ∆H < ∆E only if the number of moles of the produ products cts is grea greate terr than than the the numbe numberr of the the reactants (c) ∆H is al'ays less than ∆E
(d) The relati relations onship hip depend depends s on the capacit capacity y of the vessel 3.
4.
5.
(d) ∆H < ∆E only if the number of moles of the products is less than the number of moles of the reactants
.hich .hich of the follo'ing follo'ing is al'ay al'ays s negat negative ive for e"othermic reaction: 11.
(a)
∆H
(b)
∆S
(c)
∆G
(d) *one *one of of thes these e
The relation relation bet'een bet'een ∆E and ∆H is
(a) avoisie avoisierr and aplace aplace la' la'
(a) ∆H = ∆E − P ∆V
(b) ∆H = ∆E + P ∆V
(b) (b) Hess Hess%s %s la' la'
(c) ∆E = ∆V + ∆H
(d) ∆E = ∆H + P ∆V
(c) (c) @oul @oule% e%s s la' la'
t constan constantt T and and P& 'hich one of the follo'ing statements is correct for the reaction&
CO(g) +
1 2
(d) eAcha eAchateli telier%s er%s principl principle e 12.
O2(g) → CO2(g)
(b)
∆H > ∆E
(c)
∆H < ∆E
(b) Cons Conserva ervation tion of mass (c) #irst la' of of thermody thermodynamic namics s (d) *on *one e of the the above above 13.
#or the reaction of one mole of /inc dust 'ith one mole mole of sulph sulphuri uric c acid acid in a bomb bomb calor calorime imeter ter&& ∆ and w correspond to (a) ∆ < 0, w = 0
(b) ∆ = 0, w < 0
(c) ∆ > 0, w = 0
(d)
∆ < 0, w > 0
14.
.hich is not the correct relation bet'een bet'een enthalpy
8.
∆H = ∆E +
(c)
∆H = ∆E −
P ∆V
(b)
P ∆V (d)
∆ H = ∆ E + n RT ∆E = ∆H −
15.
B
N2 + ;H 2 → 2NH;
(b) ∆H = ∆U
(c) ∆H < ∆U
(d) ∆H > ∆U
.hich of the follo'ing is the correct euation
∆U = ∆W + ∆Q
(b)
∆W = ∆U + ∆Q
(d) *one *one of of thes these e
Hess Hess la' is appli applicab cable le for the dete determ rmina inatio tion n of heat of
The la' of avoisier avoisier and aplace illustrates illustrates
(a) eaction
(b) #ormation
(a) The principl principle e of conservation conservation of energy energy
(c) Transition
(d) ll of these
16.
(c) The princip principle le of conserva conservation tion of matter matter (d) (d) $ui $uiva vale lenc nce e energy
10.
reaction
(a) ∆H = 0
(c)
P ∆V
(b) $uivalence $uivalence of mechanical mechanical and thermal energy energy
9.
the
(a) ∆U = ∆Q − W
(∆H ) and intrinsic energy ( ∆E) (a)
Consider
carried out at constant temperature and pressure9 !f ∆H and and ∆U are the enthalpy and internal ener energy gy change changes s for the reactio reaction& n& 'hich 'hich of the follo'ing e"pression is true
(d) ∆H = ∆E
7.
Hess%s la' of constant heat summation in based on (a) E = mc2
(a) ∆H is independent of the physical state of the reactants of that compound
6.
>The resultan resultantt heat change change in a reactio reaction n is the same same 'het 'hethe herr it ta,es ta,es place place in one or seve several ral stages9? This statement is called
of
mech mechan anic ical al
and and
chem chemic ical al 17.
$nthalpy for the reaction C + O2 → CO2 is (a) -ositive
(b) *egative
(c) ero
(d) *one
7uring an isothermal e"pansion e"pansion of an ideal gas its
#or the reaction N 2 + ;H 2 < 2NH ; = ∆H =
(a) !nterna !nternall energy energy increases increases
(a) ∆E − RT
(b) ∆E − 2RT
(b) $nthalpy $nthalpy decrea decreases ses
(c) ∆E + RT
(d) ∆E + 2RT
!f ∆H is the change change in enth enthalp alpy y and ∆E the chan change ge in inte interrnal nal ener energy gy acco accomp mpan anyi ying ng a gaseous reaction (a) ∆H is al'ays greater than ∆E
(c) $nthalpy $nthalpy remai remains ns una+ec una+ected ted (d) $nthalpy $nthalpy redu reduces ces to /ero /ero 18. The 'or, done in ergs ergs for the reversible reversible e"pansion e"pansion
of one mole of an ideal gas from a volume of 10 litres to 20 litres at 25o C is (a) 29;0;× 2ED× 090D2log2
Thermodynamics Thermodynamics and Thermochemistry 160
(b) !nterna !nternall energy energy decreases decreases
(b) 2ED× 10F × D9;1× 29;0;log2
(c) !nterna !nternall energy energy increa increases ses
(c) 29;0;× 2ED× 090D2log095 F
(d) D9;1× 10 × 2ED− 29;0;log095 (e) 29;0;× 2ED× 2 log 2 19. The la' of conservation conservation of energy energy states states that
(a) (b) (c) (d)
The internal internal energy energy of a system is constant The heat heat content content of a system system is constant constant $nergy $nergy is neither neither created created nor destroy destroyed ed There There is an euivale euivalence nce bet'een bet'een energy energy and
mass 20. The enthalpies enthalpies of the elements in their standard states are assumed to be (a) ero ero at at 2ED 2ED G (b) nit nit at 2ED 2ED G (c) ero ero at all temp temperat erature ures s (d) ero ero at 2F; 2F; G 21. The heat Q for a reaction at constant volume is
eual to (a) H P
−
HR
(b) H R
(c) E P − E R 22.
23.
24.
−
HP
(d) *one *one of these these
.hich of the follo'ing e"pressions represents the rst la' of thermodynamics (a)
∆E = − q +
(c)
∆E =
W
q + W
(b) ∆E = q − W (d) ∆E = −q − W
!n a reversible isothermal process& the change in internal energy is (a) e ero (b) -o -ositive (c) *egative (d) *one of these schema hemattic plot lot of
(d) $ntropy rst increases increases and then decreases decreases 27. The internal internal energy energy of a substance substance (a) !ncreases !ncreases 'ith increase in temperature temperature (b) 7ecreases 7ecreases 'ith increase in temperature temperature (c) Can be calcu calculated lated by by the relat relation ion E = mc2 (d) emains una+ected 'ith change in temperature 28. The relation bet'een bet'een change in internal energy energy (∆E) & chan change ge in enth enthal alpy py
done (W (W ) is represented as (c) ∆E = W − ∆H (d) ∆E = ∆H + W 29. The enthalpy of neutrali/ation neutrali/ation of 'hich of the follo'ing acids and bases is nearly −1;9H Kcal (a) HCN and HCN and NaOH (b) HCl and HCl and KOH (c) HCl and HCl and NaOH (d) HCl and HCl and NHIOH 30. .or, done during isother isothermal mal e"pansi e"pansion on of one mole of an ideal gas from 10 atm to atm to 1 atm at atm at ;00 K is is (Jas constant K 2) (a) (a) E;D9 E;D9D D cal9 cal9 (b) 11;D9D cal9 cal9 (c) (c) 1;D1 1;D19D 9D cal9 cal9 (d) 15 15D19D cal. 31. @ouleLThomson @ouleLThomson e"pansion e"pansion is (a) !sobaric (b) !soenthalpic (c) !sothermal (d) *one of these 32.
(b) 2SO2 (g) + O2 (g) < 2SO ; (g) (c) H 2(g) + I 2(g) < 2HI (g) (d) H 2 (g) +
90 q
33.
34. 195O10A;
1T (G A1)
290O10A;
2
O2 (g) < H 2O(l)
!n an adiabatic e"pansion of an ideal gas (a) W = −∆E
(b) W = ∆E
(c) ∆E = 0
(d) W = 0
#or the reaction <
(a) $"othe $"othermic rmic
2CO 2 (g) + 2H 2O(l) at
(b) $ndothe $ndothermic rmic
pres pressur sure& e& ∆H = −DFI! 9 Then Then the the chang change e in
(c) 8ne 'ith negligible enthalpy change
internal energy (∆E) is M9
(d) Highly spontaneous spontaneous at ordinary temperatur temperature e
(a) (a) A DFI DFI !
(b) (b) A DF1 DF195 95; ; !
Hess la' of heat summation includes
(c) (c) A DF9 DF9IF IF !
(d) (d) N DFI DFI !
(a) !nitial !nitial reac reactant tants s only only
35.
o
2 5C
and 1 atm9 atm9
(c) #inal product products s only only
!n a closed insulated container& a liuid is stirred 'ith a paddle to increase its temperature9 !n this process& 'hich of the follo'ing is true
(d) !nterme !ntermediat diates es only
(a)
n ideal gas at constant temperature and pressure e"pands& then its
(c) ∆E = W ≠ 0& Q = 0 (d) ∆E = Q ≠ 0& W = 0
(b) !nitial reactants reactants and nal products
26.
1
CH ;COOH (l) + 2O 2(g)
The reaction reaction must be
25.
!n 'hich of the follo'ing ∆E = ∆H (a) N 2O I (g) < 2NO 2 (g)
temperature for a reaction is sho'n belo'
290
(b) W = ∆E − ∆H
(a) ∆H = ∆E + W
lnK eq versu versus s inver inverse se of
e K n l
(∆H ) and 'or, 'or,
(a) !nterna !nternall energy energy remains remains same same
36.
∆E =
W = Q
=
0
Hess la' is based on
(b) ∆E ≠ 0& Q = W = 0
Thermodynamics and Thermochemistry Thermochemistry 161 Thermodynamics
(a) (b) (c) (d) 37.
a' of of conserva conservation tion of of mass a' of conser conservati vation on of energy energy $nthalpy $nthalpy is is a state state func function tion *one *one of of thes these e
44.
#or the reaction&
C ; H D (g) + 5O2 (g) → ;CO 2(g) + IH 2O(l)
45.
at constant temperature& temperature& ∆H − ∆E is
38.
(a) A RT
(b) N RT
(c) A ;RT
(d) N ;RT
ccor ccordin ding g to HessPs HessPs la'& la'& the heat heat of react reaction ion depends upon
46.
(a) !nitial condition of reactants reactants (b) !nitial and and nal nal conditions conditions of reactants reactants (c) !nterme !ntermediat diate e path of the react reaction ion (d) $nd condit conditions ions of reacta reactants nts 39. The value of ∆H − ∆E for the follo'ing reaction
47.
D9;1I× ;00× (−2)
40.
(c) 500 !
(d)) 0 (d 00 0 !
.or, done during isother isothermal mal e"pansi e"pansion on of one mole of an ideal gas from 10 atom9 to 1 atm at ;00G is (a) (a) IE;D IE;D9D 9D ! ! (b) (b) I1;D I1;D9D 9D ! ! (c) (c) 5FII 5FII91 91 ! ! (d) (d) 25F 25F92 92 ! ! !f gas& gas& at consta constant nt tempe temperat rature ure and pres pressur sure e e"pands then its (a) $ntropy increases increases and then decreases decreases (b) !nterna !nternall energy energy increases increases (c) !nterna !nternall energy energy remains remains the the same #or the reaction
(a) ∆H = ∆E
(b) ∆H > ∆E
(c) ∆H < ∆E
(d) *one *one of of thes these e
$nthalpy (H ) is eual to (a) !nterna !nternall energ energy y ($) ($) (b) -roduct -roduct of pressure pressure (-) and and volume (6) (6) of gas
(a) N 2OI (g) < 2NO 2 (g)
(c) !nterna !nternall energy energy ($)N-6 ($)N-6
(b) 2SO2 (g) + O2 (g) < 2SO ; (g)
(d) .or, (.) done done by a syste system m
(d) H 2(g) +
42.
48.
#or 'hich of the follo'ing ∆E = ∆H
(c) H 2 (g) + Cl 2 (g) < 2HCl(g)
41.
(b)) I0 (b I00 0 !
PCl5(g) → PCl ;(g) + Cl2(g)
(b)
(c) D9;1I× 2F× (−2) (d) D9;1I× ;00× (2)
(a) ;0 ;00 0 !
(d) !nterna !nternall energy energy decreases decreases
at 2Fo C 'ill be 2NH ; (g)→ N 2 (g) + ;H 2 (g) (a) D9;1I× 2F;× (−2)
system absorb 00 ! ! of of heat and 'or, euivalent to ;00 ! ! on on its surroundings9 surroundings9 The change in interna internall energy is
1 2
49.
o
50.
of
isobutylene
(c) = 0
(d) < ∆E o
8ne mole of an ideal gas is allo'ed to e"pand reversibly and adibatically from a temperature of during the proc process ess is 2Fo C 9 !f the 'or, done during ; !
(c) ∆E = 0
(d) W = 0
(CV
o
51.
& then then nal nal temp temper erat atur ure e of the the gas gas is
=
20 ! K )
(a) 100 K
(b) (b) 150 150 K
(c) 1E5 K
(d) (d) 255 255 K
.hich .hich of the follo' follo'ing ing is corre correct ct regar regardin ding g the internal energy of a substance
(a) (a) 0& A E5 E59D 9DI I cal
(a) !t is a state state function function
(b) (b) A E5 E59D 9DI I cal& cal& N E59DI cal
(b) !t increases increases 'ith increase in temperature temperature
(c) (c) N D59 D595D 5D cal, A D595D cal
(c) !t can be calcul calculated ated by e"pe e"perimen rimentt
(d) (d) A D5 D595 95D D cal, A D595D cal
(d) !t remains temperature
43. The 'or, done by a system is D #o$le, 'hen I0
#o$le heat is supplie supplied d to it9 .hat is the increase increase in internal energy of system (a) 25 !
(b) ;0 !
(c) ;2 !
(d) 2D !
is
mol−1 9 The value of ∆H o is
(b) > ∆Eo
(b) ∆S = 0
2F C& one mole of an ideal gas is compres compressed sed isotherm isothermally ally and reversib reversibly ly from a pressure of 2 atm atm to 10 atm9 atm9 The values of ∆E and q are (R = 2)
combustion
(a) = ∆E o
(a) ∆H = 0
t
of
− % !
O 2 (g) < H 2O(l)
8ne mole of an ideal gas is allo'ed to e"pand free freely ly and and adia adiaba bati tica call lly y into into vacu vacuum um unti untill its its volume has doubled9 statement 'hich is not true concerning this e"pression is
∆E
52.
una+ected
'ith
change
#or the gaseous reaction&
N2OI
→
2NO2
(a) ∆H < ∆E
(b) ∆H = ∆E
(c) ∆H = 0
(d) ∆H > ∆E
in
Thermodynamics Thermodynamics and Thermochemistry 162 53.
2C + O2
→
2CO= ∆H
= −220!
.hich of the follo'ing statement is correct for this reaction
4.
(a) Heat of combustion of of carbon is 110 ! (b) eactio eaction n is e"other e"othermic mic (c) eactio eaction n needs needs no initiatio initiation n (d) ll of these these are corr correct ect 54.
5.
n ideal gas e"pands e"pands in volume from 1× 10−;m; to
;0 00 K again against st a consta constant nt 1× 10−2m; at ;
(b) n increase increase in the total entropy entropy of the system system (c) decrease decrease in the total entropy of the system
pressure of 1× 105 Nm−2 9 The 'or, done is (a) 2F0 ! (c) AE00 ! 55.
6.
!nternal energy is (a) (b) (c) (d)
56.
(b) (b) AE00 AE00 ! (d) (d) E00 !
-artly potenti potential al and partly ,ineti ,inetic c Totally otally ,inetic ,inetic Totally otally poten potential tial *one *one of of thes these e
(a) N2 + ;H 2 < 2NH ; (b) N2 + O2 → 2NO
PCl5
→
7.
(d)
PCl; + Cl2
57. The 'or, done during the e"pansion e"pansion of a gas from
a volume of Idm; to Hdm; against a constant e"ternal pressure of is ( ;at = 101 1& atm 101 9;2 !
58.
(b) (b) A;0I A;0I ! !
(c) A !
(d) (d) A0D A0D ! !
#or
the
reaction&
8.
)
(a) N ;0 ;0I !
*(') + 2)(g)
→
IC(') + ((l) 9
(b) ∆H = ∆U + ;RT
(c) ∆H = ∆U + RT
(d) ∆H = ∆U − ;RT
IInd & IIIrd Law of thermodynamics and Entropy #or a reversible spontaneous change ∆S is
(c) 2.
3.
∆E
T
q T
(b)
Cl2(g)
→
2HCl(g) is
(a) N 5I09; (b) N F2F9; (c) A 19E (d) N 1E9D .hich of the follo'ing is the least random state of 'ater (a) !ce (b) iuid iuid 'ater 'ater (c) (c) 3tea team (d) ll prese present nt same rando random m state .hic .hich h one one of the the foll follo' o'in ing g proc proces ess s is nonL nonL spontaneous (b) eactio eaction n bet'e bet'een en H 2 and O2 to form 'ater
(a) ∆H = ∆U
(a)
+
(a) 7issol 7issoluti ution on of of C$SOI in 'ater
∆H and ∆U are related as MMM
1.
(d) *one *one of of thes these e The entropy values (in !K L1 molL1) of H2(g 2(g) K 1;09& Cl2(g 22;90 and and HCl(g) K 1D9F 1D9F at 2ED 2ED K and 1 2(g) K 22;90 atm pres pressu sure re99 Then Then entr entrop opy y chan change ge for for the the reaction
H 2(g)
#or 'hich of the reaction ∆H = ∆E
(c) 2Na + Cl2 → 2NaCl
(d) (d) nid nidir ire ectio ctiona nall from from the the high higher er to lo'e lo'err temperature i"i i"ing ng of nonL nonLrreact eactin ing g gase gases s is gene genera rall lly y accompanied by (a) 7ecrea 7ecrease se in entropy entropy (b) !ncrease !ncrease in entr entropy opy (c) Chang Change e in entha enthalpy lpy (d) Change Change in free free energy energy n irreversible process occuring isothermally isothermally in an isolated system leads to (a) ero ero ent entro ropy py
P ∆V T
(d) RT log K
.hen disorder of a system increases& the change is said to be (a) $"othermic (b) *onLspontaneous (c) $ndothermic (d) 3pontaneous The spontaneous spontaneous Qo' of heat is al'ays al'ays (a) #rom lo' to to high pressu pressure re (b) #rom high high to high pressu pressure re (c) (c) nid nidir irec ecti tion onal al from from lo'e lo'err temp temper erat atur ure e to higher temperature
9.
(c) .ater Qo'ing Qo'ing do'n hill (d) #lo' #lo' of elec electri tric c curr curren entt from from lo' poten potentia tiall to high potential .hich .hich of the follo'ing follo'ing is /ero /ero durin during g adiaba adiabatic tic e"pansion of the gas (a) ∆T
(b) ∆S
(c) ∆E (d) *one *one of these these 10. The entropy of crystalline substances substances at absolute /ero /ero going going by the third la' of thermod thermodynam ynamics ics should be ta,en as (a) 100 (b) 50 (c) ero (d) 7i+erent 7i+erent for di+erent di+erent substances substances 11. !n 'hich state& the matter have highest entropy (a) 3o 3olid (b) iuid (c) Ja J as (d) $ $ual in all 12. .hich of the follo'ing pairs of a chemical reaction reaction is certain to result in spontaneous reaction : (a) $"othermic $"othermic and decreasing decreasing disorder disorder (b) $ndothermic $ndothermic and increasing increasing disorder (c) $"othermic $"othermic and increasing increasing disorder disorder (d) $ndothermic $ndothermic and decreasing decreasing disorder disorder
Thermodynamics and Thermochemistry Thermochemistry 163 Thermodynamics 13.
.hen .hen one mole of monoat monoatomi omic c ideal ideal gas at T K unde underg rgoe oes s adiaba adiabatic tic chang change e under under a consta constant nt e"ternal e"ternal pressure of 1 atm changes volume from 1 litre to 2 litre9 The nal temperature temperature in Gelvin Gelvin 'ould be be (a)
T
(b) T N N
2(2 5 ;)
(c) T 14.
(d) T −
; × 090D21 ; × 090D21
(c)
(b)
1D + 100
1D + ;F;
(d)
1 1D+ × 2 ;F;
+ ;F;
15. The
16.
22.
23.
∆S for the vaporisation of 1 mol of 'ater is
DD9; ! !mole ole K 9 The value of ∆S condensation of 1 mol of mol of vapour 'ill be
for for the the 24.
2
(a) DD9; ! 9; !mol K
(b) (DD9;) ! !mol K
(c) (c) A DD9; DD9; ! !mol K
(d)
;F; ;F;K
26.
N ve but 27.
also A ve ve ∆S is also
but
∆H > T ∆S
(c) ∆H is A ve ve = ∆S is N ve (d) ∆H is N ve = ∆S is A ve 18.
19.
steam&
!f the enthalpy of vapori/ation for 'ater is 1D95 ! mol−1 & the entropy of its vapori/ation 'ill be mol−1 (a) 095 !K −1mol
mol−1 (b) 190 !K −1mol
mol−1 (c) 195 !K −1mol
mol−1 (d) 290 !K −1mol
and
.hich .hich of the follo' follo'ing ing state stateme ment nt is true9 true9 The The entropy of the universe (a) !ncreases !ncreases and tends to'ards ma"imum value (b) 7ecrea 7ecreases ses and tends tends to be /ero /ero (c) emain emains s const constan antt (d) 7ecreases 7ecreases and increases increases 'ith 'ith a periodic rate
−1
∆H a- = ;F9;! mol mol
1
at
K
(b)
−1
! mol mol−1K −1 100 (c) 100
T ∆S is A ve ve =
100o C
9 The entropy change for the process is
−1
17. The occurrence occurrence of of a reaction is impossible if
(b) ∆H
at
(b) ∆H = 0
mol−1K −1 111 9E ! mol (a) 111
(d) N 2(g) + O2(g) → 2NO(g)
∆H <
to
;F9; ! mol mol
is also
at
(c) ∆H = ∆E (d) ∆H = T ∆S 25. The enthalpy change for the transition of liuid 'ater
(c) C(') + O2(g) → CO 2(g)
∆S
react reaction ion
(a) 3pontaneous (b) eversible (c) !rreversible (d) *onLspontaneous The total entropy change for a system and its surroundings increases& if the process is (a) eversible (b) !rreversible (c) $"othermic (d) $ndothermic #or chemical reactions& the calculation of change in entropy is normally done (a) t const constant ant pres pressur sure e (b) t constan constantt temperat temperature ure (c) t constant constant temperature temperature and pressure pressure both (d) t constant constant volume volume .hen .hen the value of entr entropy opy is grea greater ter&& then then the ability of 'or, (a) !s ma"imum (b) !s minimum (c) !s medium (d) *one of these .hich .hich of the follo'in follo'ing g is true true for the reactio reaction n
(a) ∆E = 0
1 O 2(g) → CaO(') 2
is Nv Nve =
the
atmosphere
1 ! !mol K DD9;
(b) CaCO;(') → CaO(') + CO2(g)
(a) ∆H
-red -redict ict
H 2O(l) < H 2O(g)
#or 'hich reaction from the follo'ing& ∆S 'ill be ma"imum (a) Ca(') +
respe respecti ctive vely ly99
2EDK is
21.
2
.hen enthalpy and entropy change for a chemical cal an reaction are − 295× 10; cal and F9I cal
deg−1
2
E90 gm of H 2O is vaporised vaporised at 100o C and 1 atm pressure9 atm pressure9 !f the latent heat of vaporisation of 'ater is + ! g & then ∆S is given by (a)
20.
mol−1K −1 (d) FI9H ! mol
.hen a solid is converted into liuid& entropy (a) 4ecomes /ero (b) emains the same (c) 7ecreases (d) !ncreases !n a sponta spontane neous ous proce process& ss& the entr entrop opy y of the system and its surroundings (a) $uals /ero (b) 7ecreases (c) !ncreases (d) emains constant
28. The positive positive value of ∆S indicates that
(a) (b) (c) (d) (d) position 29.
The system system becomes less disordered disordered The system system becomes becomes more more disordere disordered d The system system is in euil euilibriu ibrium m position position The The syst system em tend tends s to reac reach h at eui euili libr briu ium m
#or reaction 2Cl(') → Cl 2(') & the signs of ∆H and ∆S respectively are (a) N& A (b) N& N (c) A& A (d) A& N
;DH! 9 .hat is entropy 30. The enthalpy enthalpy of 'ater is ;DH
of 'ater (a) 095 !
(b) (b) 190; 190; !
Thermodynamics Thermodynamics and Thermochemistry 164
(c) 195 ! 31.
(d) (d) 2290 22905 5 ! 40.
#or 'hich of the processes is ∆S negative (a) H 2(g) → 2H (g)
32.
(a) (a) -osit ositiv ive e ∆H and positive ∆S
(b) N 2(g)1atm→ N 2(g)D atm
(b) (b) *ega *egati tive ve ∆H and negative ∆S
(c) 2SO;(g) → 2SO2(g) + O2(g)
(c) (c) -osit ositiv ive e ∆H and negative ∆S
(d) C(d/amond ) → C(gra-./te )
(d) (d) *ega *egati tive ve ∆H and positive ∆S #ollo'ing data is ,no'n about melting of a compound *) compound *)99 ∆H = E92 ! mol−1 &
!dentify the correct statement regarding entropy
41.
(a) t 0o C & the entropy of a perfectly crystalline substance is ta,en to be /ero (b) t absolute absolute /ero of temperat temperature ure&& the entropy entropy of a perfectly crystalline substance substance is +,e (c) t absolute absolute /ero /ero of temperat temperature ure&& the entropy entropy of all crystalline substances is ta,en to be /ero (d) t absolute absolute /ero of temperat temperature ure&& the entropy entropy of a perfectly crystalline substance is ta,en to be /ero 33.
34.
35.
36.
37.
8ne mole of an ideal gas at ;00 ;00K is e"panded isothermally from an initial volume of 1 litre to 10 litre litres9 s9 The change change in ener energy gy for this this proc process ess is −1 −1 (R = 2 calmol K ) (a) (a) 1;9 1;9F F cal (b) (b) D509 D5092 2 cal (c) (c) 1;D1 1;D191 91 cal (d) (d) er ero !f E00 ! g of heat is e"changed at boiling point of 'ater& then 'hat is increase in entropy (a) I;9I !0mole 9I !0mole (b) (b) DF92 DF92 !0mole !0mole (c) E00 !0mole (d) (d) er ero container has hydrogen and o"ygen mi"ture in ratio of I B 1 by 'eight& then (a) !nternal energy energy of of the mi"ture mi"ture decreases decreases (b) !nternal energy energy of of the mi"ture mi"ture increases increases (c) $ntropy $ntropy of the mi"tur mi"ture e increase increases s (d) $ntropy of the mi"ture decreases decreases !f 09F5 mole of an ideal gas e"pands e"pands isother isothermall mally y o at 2F C from 15 l/tre' to l/tre' to 25 l/tre', the ma"imum 'or, obtained is (a) D9I0 D9I0 ! (b) (b) E9;I E9;I ! ! (c) 109D 9D ! (d) (d) 109I 109I; ; ! !n 'hich 'hich of the follo'ing follo'ing condition conditions s a chemica chemicall reaction can not occur
∆S = 0900D! K
(c) ∆H increases and ∆S decreases (d) ∆H decreases and ∆S increases n
engin gine
25o C
ope operati ratin ng
bet'e t'een
150o C
and
ta,es 50 5 00 ! heat from a higher temperat temperature ure reservo reservoir ir if there there are no frictional frictional losses& then 'or, done by engine is (a) 1IF9F 1IF9F ! (b) (b) 15F9 15F9F5 F5 ! ! (c) (c) 159 159D5 D5 ! ! (d) (d) 1E9 1E9E5 E5 ! ! 39. The entropy of a perfectly crystalline solid at absolute /ero is (a) -ositiv ositive e (b) *ega *egativ tive e
mol−1 9 !ts melting melting point is
(a) F; K
(b) (b) 1050 1050 K
(c) 1150K
(d) 1150o C
an aver averag age e pres pressu surre of 09 09 atm9 atm9 7uri 7uring ng this this proce process ss 10 ! ! of heat is liberated9 The change in internal energy is (a) (a) A 291 291 ! (b) (b) 1291 12915 5 ! ! (c) (c) 291 91 ! (d) (d) 1019 1019; ; ! 43. The standard entropies entropies of
O 2 (g)
are
21;95&
CO2 (g)&C(') and
59E0
and
205 !K
−1
respective respectively ly99 The standard standard entropy entropy of formation formation of
CO 2 (g) is (a) 19DH !K −1
(b) 19EH !K −1
(c) 29D1 !K −1
(d) 29DH !K −1
44.
.hich of the follo'ing endothermic processes are spontaneous (a) elting of ice (b) $vaporation of 'ater (c) (c) Heat Heat of comb combus usti tion on (d) (d) 4oth 4oth (a) (a) and and (b) (b)
45.
#or #or the reaction reaction H 2O(') < H 2O(l) at 0o C and normal pressure (a) ∆H > T ∆S
46.
(b) ∆H = T ∆S
(c) ∆H = ∆G (d) ∆H < T ∆S 8ne 8ne mole mole of an idea ideall gas gas is allo' allo'ed ed to e"pa e"pand nd reversibly and adiabatically from a temperature of !& 2Fo C 9 !f the 'or, done during the process is ; !& the nal temperature 'ill be eual to
(C ,
=
20!K −1)
(a) 150 150 K
(b) ∆H and ∆S decrease and ∆H > T ∆S
−1
500cc to 42. The volume of a gas decreases decreases from 500 ;00 ;00cc 'hen a sample of gas is compressed by
(a) ∆H and ∆S increase and T ∆S > ∆H
38.
(c) ero (d) * *o ot denite .hich of the follo'ing conditions 'ill al'ays lead to a nonLspontaneous nonLspontaneous change
(b) (b) 100 100 K
(c) 2H9D5o C (d) (d) 2E5 2E5 K 47. The entrop entropy y change change&& in the conversio conversion n of one mole mole of liu liuid id 'ater 'ater at ;F; ;F; K to vapour vapour at the the same same temperature is (atent heat of vapori/ation of 'ater& ∆H ,a- = 2925F! g)
48.
(a) 1059E 1059E ! −1
(b) 10F9E ! −1
(c) 10D9E ! −1
(d) 10E9E ! −1
heat engine absorbs absorbs heat Q1 at temperature
T 1 and and heat heat Q 2 at temper temperatu ature re T 2 9 .or, done by the engine is (Q1 + Q2 ) 9 This data
Thermodynamics and Thermochemistry Thermochemistry 165 Thermodynamics
(a) (a) 6iol 6iolat ates es !st la' of thermodynamics
57.
(b) (b) 6iol 6iolat ates es ! la' of thermodyn thermodynamics amics if Q1 is A e st
(c) (c) 6iola iolate tes s ! st la' of thermodyn thermodynamics amics if Q 2 is A
49.
e (d) 7oes 7oes not viol violate ate !st la' of thermodynamics $ual volumes of monoatomic and diatomic gases at same same initia initiall tempe temperat ratur ure e and press pressur ure e are are mi"ed9 The ratio of specic heats of the mi"ture (C - C , ) 'ill be
(a (a) 1 (b) 2 (c) 19F (d) 195 50. The la' formulated formulated by 7r 7r9 *ernst *ernst is (a) #irst la' of of thermody thermodynamic namics s (b) 3econd 3econd la' of thermody thermodynami namics cs (c) Third Third la' of of thermod thermodynam ynamics ics (d) 4oth 4oth (a) (a) and and (b) (b) 51. The unit of entropy entropy is mol−1 (a) ! mol
mol−1 (b) !K mol
mol−1K −1 (c) ! mol
(d) !
−1
58.
53.
(c) 59.
61.
2925F! gmR (b)
62.
−
F0 !K
−1
1
mol mol−
1 mol− (b) D09F !K −1mol
(d)
+ 10 9F !K
−1
mol mol−1
8ne mole mole of 'ater 'ater at 100 100o C is converted into steam at 100 100o C at a constant pressure of 1 atm9 The change in entropy is Sheat of vaporisation of 'ater at 100o C = 5I0cal gmR (b) 1D9F (d) 290
#or a carnot engine& the source is at 500 500K and the the sin, in, at ;00 .hat is eci ecien ency cy of this this ;00K 9 .hat engine (a) 092 (b) 09I (c) 09 (d) 09; Heat reuire reuire to raise the temperature of 1 mol of a substance by 1o C is called (a) 3pecic heat (b) olar heat capacity (c) .ater euivalent (d) 3pecic ic gravity a"imum entropy 'ill be in 'hich of the follo'ing (a (a) !ce (b) iiuid 'ater (c) 3no' (d) .a .ater vapours
CO2(g)& C(') and
are 21;95& 59FI0 and 205 !K −1 respectively9 The standard entropy of formation of CO 2 is
.hich one of the follo'ing has ∆S o greater than /ero 64.
(a) CaO + CO2(g) < CaCO;(') (b) NaCl(aq) < NaCl(') 65.
(a) 29FH !K −1
(b) 2912 !K −1
(c) 1912 !K −1
(d) 19I0 !K −1
.hich la' of thermodyanamics help in calculating entropy at di+erent temperatures (a) #irst la' (b) 3econd la' (c) Third la' (d) eroth la' $ntropy is ma"imum in case of (b) .a .ater at 0o C
(a) 3t 3 team
(d) N 2 (g) + ;H 2 (g) < 2NH ; (g) 55. The molar heat capacity of 'ater at constant
pressure is F5 !K −1mol−1 9 .hen 190 ! of ! of heat is suppl supplie ied d to 100 g of 'ate 'aterr 'hic 'hich h is free free to e"pand the increase in temperature of 'ater is (a) 9 K (b) (b) 192 K (c) 29I K (d) (d) I9D K 56. The 'or, done to contract a gas in a cylinder& is I2 #o$le'9 #o$le'9 1 2D 2D #o$le ener energy gy is evolv evolved ed in the process9 .hat 'ill be the internal energy change in the process (a) N 5E 5E0 #o$le' (b) (b) A ;;I ;;I #o$le' (c) N ;;I #o$le' (d) (d) A 5E0 5E0 #o$le'
+ F0
O2(g)
(c) n increa increase se in heat heat of vapori/a vapori/ation tion (d) n increase increase in in free ener energy gy
− (c) NaNO; (') < Na+ (aq) + NO; (aq)
(aq) → → H 2O(l)
−109F
63. The standard entropies entropies of
(a) n incre increase ase in in entrop entropy y (b) decrea decrease se in entr entropy opy
54.
S o (2EDK ) K − 1mol−1
−
(a) H09; !K −1mol−1
60.
K −1mol1
(a (a) 0911E ! 0910E ! (c) 0912 912E ! (d) (d) 0912 09120 0 ! .hen a liuid boils& there is
+ OH
3tandard entropy change for the above reaction is
1 mole mole of liuid 'ater 'ater at ;F; K to to vapour at the same temperature 'ill be =
H + (aq)
(b) .ater (d) ercury
(a) D9FI (c) 2I 2I90
52. The entropy entropy changed involved involved in the conversion of
S∆H vap
Highest entropy is in (a) Hydrogen (c) Jraphite
66.
(c) (c) .ater ater at Io C (d) !ce Consid Consideri ering ng entr entropy opy (3) (3) as a ther thermod modyna ynamic mic parameter& the criterion for the spontaneity of any process is (a)
∆S'1'tem>
0 only
(b)
∆S'$rro$nd/n g' >
0 only
(c) ∆S'1'tem+ ∆S'$rro$nd/n g' > 0 (d) 67.
∆S'1'tem− ∆S'$rro$nd/n g' >
0
process is ta,ing place at constant temperature and pressure9 Then
Thermodynamics Thermodynamics and Thermochemistry 166
(a) ∆H = ∆E
(b) ∆H = T ∆S
7.
−1
K 9 The boiling point of the liuid at 1
atm is atm is (a) 250K (c) I50K
8.
(b) I00K (d) 00K
Heat of reaction 9. 1.
!f C + O2 → CO2 + EI92 cal
H2 +
1 O2 2
→
CH I + 2O2
2.
→
−1
! mol mol 1H
(a)
K
−1
is is
)+ C(graphite
CO(g) +
(b) ;F5K
;F5 C
(d) 102 102o C The enthalpy enthalpy of fusion of ice per mole (a) 1D ! (b) D ! (c) D0 ! (d) ! !n 'hich of the follo'ing neutralisation reactions& the heat of neutralisation 'ill be highest
4.
11.
(a) NH IOH and CH ;COOH (b) NH IOH and HCl
12.
(c) NaOH and CH ;COOH (d) NaOH and HCl 5.
!f S + O2 → SO2= (∆ H = −2ED92)
1 SO2 + O2 → SO;=(∆H = −ED92) 2 SO; + H 2O → H 2SOI = (∆H = −1;092) H2 +
1 2
O2
→
H 2O=(∆H
9;) = −2DF
13.
14.
then then the the enth enthal alpy py of form format atio ion n of H 2SOI at 2EDG 'ill be 9F ! (a) −I;; 6.
(b)
→
HCO2(g) + ;H 2O(l)=∆H
= −;2HI 9H!
9; ! −H50
9E ! ;20 95 ! (c) +;20 (d) −D1; #rom Girchho+%s euation 'hich factor a+ects the heat of reaction (a) -ressure (b) Temperature (c) 6olume (d) olecularity
1 O2(g) → CO(g)=∆H 2
11095! = −110
1 O2(g) → CO 2(g)=∆H 2
= −2D; 92!
#rom the above reaction& the heat of reaction for C(graphite ) + O2(g) → CO2(g) 'ill be
(c) 2F;K
3.
1 O2 2
(a) (a) D19 D1915 15 ! (b) (b) 1;2 1;29; 9; ! (c) (c) 52D 52D92 92 ! (d) (d) 2IID 2IID9I 9I5 5 ! 10. Thermochemical Thermochemical reactions reactions
& the boiling point of the liuid is
o
+F
.hich of the follo'ing uantities of heat energy 'ill be evolved 'hen ;Eg C H H H are burnt
CO2 + 2H 2O + 2109D cal
then the possible heat of methane 'ill be (a) IF9; cal cal (b) 2090 (b) 2090 cal (c) I59E cal (d) (d) A IF9; IF9; cal olar heat of vaporisation of a liuid mol−1 9 H! mol !f the entropy change
and
of NaOH and HCl (a) ess (b) ore (c) $ual (d) 7epends on pressure n e"othe otherrmic mic react eactio ion n is one one in 'hic 'hich h the the reacting substances (a) Have more more energy energy than the the products products (b) Have less less energy energy than than the products (c) re at a higher temperature temperature than the product product (d) *one *one of the the above above The heat evolved in the combustion of ben/ene is given by
CH H H
H 2O + HD9; cal
KOH
HNO; as compared to molar neutrali/ation heat
(c) ∆H = 0 (d) ∆S = 0 68. The enthalpy of vapouri/ation of a liuid is −1 mol ;0! mol and entr entropy opy of vapou vapouri/ ri/ati ation on is mol F5 ! mol
The molar neutrali/ation neutrali/ation heat for
15.
(a) (a) A ;E;9 ;E;9F F ! (b) (b) N ;E;9 ;E;9F F ! (c) (c) A 1F2 1F29F 9F ! (d) (d) N 1F29 1F29F F ! The follo'ing is (are) endothermic endothermic reaction reaction (a) Combusti Combustion on of of methan methane e (b) 7ecompo 7ecompositio sition n of 'ater 'ater (c) 7ehydr 7ehydrogen ogenatio ation n of ethane ethane to ethylene ethylene (d) Conversi Conversion on of graphite graphite to diamond diamond $vaporation of 'ater is (a) n endoth endotherm ermic ic change change (b) n e"ot e"other hermic mic change change (c) process process 'here 'here no no heat change change occurs occurs (d) process process accompanied accompanied by chemical chemical reaction reaction n e"othermic reaction is one 'hich (a) Ta,es place only only on heating (b) !s accomp accompanie anied d by a Qame Qame (c) !s accompa accompanied nied by a absorp absorption tion of heat heat (d) !s accompan accompanied ied by evolut evolution ion of heat heat n endothermic reaction is one in 'hich (a) Heat is convert converted ed into electric electricity ity (b) Heat Heat is abso absorbe rbed d (c) Heat Heat is is evol evolve ved d (d) Heat is convert converted ed into mechani mechanical cal 'or, .hich of the follo'ing statement is correct (a) ∆H is positive for e"othermic reaction (b) ∆H is negative for endothermic reaction (c) The heat heat of neutr neutrali ali/at /ation ion of strong strong acid acid and strong base is al'ays the same (d) The enthalp enthalpy y of fusion is negat negative ive
Thermodynamics and Thermochemistry Thermochemistry 167 Thermodynamics 16. The absolute enthalphy enthalphy of neutralisation neutralisation of the
23.
reaction
Jiven that
2C(') + 2O2(g) → 2CO 2(g)= ∆H
2gO(') + 2HCl(aq) → 2gCl2(aq) + H 2O(l) ' ill be
1 O2(g) → H 2O(l)= ∆H 2
H 2(g) +
−1
(a)ess than − 5F9;; ! mol (b) − 5F9;; ! mol−1
C 2H 2(g) + 2
(c) Jreater Jreater than − 5F9;; ! mol−1 (d) 5F9;; ! mol−1 17.
chemical euation (a) CH I (g) + 1 2O2(g) → CH ;OH(g) (b) C
24.
2H 2(g) → CH ;OH(l) (diamond)
2H 2(g) → CH ;OH(l)
(d) CO(g) + 2H 2(g) → CH ;OH (l) !f
o
∆H 3
H 2O2
fo for
an and
−1DD! mole and −2DH!
be
the
enthalpy
change
19.
H 2O
are
) + O2(g) → CO2(g)= ∆H C(graphite
26.
= 1 !
(a) ( + + 1 )! mol−1
−1 mol (b) ( + − 1 )! mol
(c) ( 1 − + )! mol−1
(d) *one *one of these these
Corr Correc ectt rela relati tion onsh ship ip bet' bet'ee een n heat heat of fusi fusion on (∆H 3$') & heat heat of vapo vapori ri/a /ati tion on (∆H a-) and heat of sublimation (∆H '$4) is
21.
∆H ,a- = ∆H 3$' + ∆H '$4
(c)
∆H '$4 = ∆H ,a- + ∆H 3$'
(d)
∆H '$4 = ∆H ,a- − ∆H 3$'
.hich of the follo'ing endothermic reaction (a) C 2H 2
+
2H 2
+22D!
$nthalpy change for reaction&
H2 +
1 2
Cl2 → HCl HCl & is called
Conversion of o"ygen to o/one represented represented by the euation ;O2 → 2O; is an endothermic reaction9
(a) (a) 591 cal (b) ess ess than than 591 591 cal (c) ore ore than than 591 591 cal (d) (d) 1;9F 1;9F cal 28. The heat of formations of CO(g) and
CO 2 (g)
are −2H9I cal cal and −EI90 cal cal respectively9 The heat of combustion of carbon mono"ide mono"ide 'ill be (a) +2H9I cal (b) −HF9Hcal (c) is
an
e"ample
of
30.
9Dcal +52
(a) (a) A 121 121 K! K! mole
(b) (b) N 121 121 K! K! mole
(c) (c) A 2I2 K! 0 mole
(d) (d) N 2I2 2I2 K! 0 K! 0 mole
Heat of neutralisation of NH IOH and HCl is (a) 1;9Fcal
!f the the enth enthal alpy py of 4 is great greate er than than of *& *& the reaction * → ) is (b) $"othermic (d) 3pontaneous
(d)
enthalpy of combustion at 25UC 25UC of H2& cyclohe"ane cyclohe"ane (CH12) and cyclohe"ene (C ( CH10) are A 2I1& 2I1& A;E20 A;E20 and and AD00 AD00 K! 0 mole mole respectively9 The heat of hydrogenation of cyclohe"ene is
;1I90! → C 2 H H = ∆E = −;1I
(d) 2H 2 + O2 → 2H 2O= ∆E + 5F19D !
−120 9Hcal
29. The
(c) N 2 + O2 → 2NO= ∆E − 1D095!
(a) $ndothermic (c) !nstantaneous
(d)
$nthalpy change ∆H accompanying the reaction (a) (a) !s nega negati tive ve (b) (b) !s posi positi tive ve (c) (c) !s /er /ero (d) 7epend 7epends s on temperat temperature ure 27. The mutual heat of neutralisation neutralisation of I0 gm of NaOH and 0 gm CH ;COOH 'ill be
(b) C + O2 → CO2 = ∆E = −;E;95!
22.
−D00!
;COOH and NaOH (d) CH
= + !
C(diamond )+ C 2(g) → CO 2(g)= ∆H
(b)
(c)
(b) NH IOH and HNO;
The heat of transition (∆H t ) of graphite graphite into
(a)
+ 1D02 !
(c) HCl and NaOH
(b) 1IH! mole (d) −ED! mole
∆H 3$' = ∆H ,a- + ∆H '$4
(b)
(a) HCl and NH IOH
mol 9 .hat 'ill of the reaction
diamond 'ould be& 'here
20.
= −1;01
(a) $nthalpy of combination (b) $nthalpy of reaction (c) $nthalpy $nthalpy of formation formation(d) (d) $nthalpy $nthalpy of fusion fusion 25. The enthalpy of neutrali/ation neutrali/ation is about 5F9; ! for the pair
2H 2O2(l) → 2H 2O(l) + O2(g) (a) −1EH! mole (c) −IEI! mole
! − 1D02
2
(c) C
18.
1 2(g) + H 2O(l)=∆H O2(g) → 2CO 2
(a)
1
(graphite)
+1 2O2(g) +
= −2DH!
Heat of formation of acetylene is
∆H ° 3 (2ED K ) of meth methan anol ol is give given n by the the
+1 2O2(g) +
= −FDF FDF!
(c) 31.
< 1;9Fca
Heat
of
(b)
> 1;9Fcal
(d) *one *one of the above above combustion
∆H
of
CH I & C 2H H& C 2H I an and C 2 H 2 gases gases are A
Thermodynamics Thermodynamics and Thermochemistry 168
2129D& A ;F;90& A ;;F90 and A ;1095 cal respec respective tively ly at the same temperatur temperature9 e9 The best best fuel among these gases is
32.
(a) CH I
(b) C 2 H H
(c) C 2 H I
(d) C 2 H 2
Heat of forma ormattion ion of
CO2(g)& H 2O(l) and
CH I (g) are
40. The heat change change for the the reaction reaction
H2 +
(b) (b) 8nly 8nly H + and OH − ions react in every case (c) The The str strong base ase and and str strong acid react act completely (d) (d) The The str strong ong base base and and str strong ong acid acid reac reactt in aueous solution 35. Heat Heat of neut neutra rali lisa sati tion on of an acid acid by a base base is highest 'hen (a) 4oth the the acid and and base are are 'ea, 'ea, (b) 4oth the the acid and base base are are strong strong (c) The acid acid is strong strong and and the base base is 'ea, 'ea, (d) The acid is 'ea, and the base is strong strong 36. The standard molar heat of formation of ethane& CO 2 and 'ater (l (l) are respectively A 2191& A EI91 and A D9; cal9 cal9 The The stan standa dard rd mola molarr heat heat of combustion of ethane 'ill be (a) A ;F ;F2 cal (b) (b) 12 cal (c) A2I0 cal (d) (d) 1D;9 1D;95 5 cal 37. .hich of the follo'ing reaction is endothermic
2CO + O2
→
H 2O is called
→
2CO2 =∆H
1;5cal is = −1;5
called
(a) Heat of of fo formation (b) Heat of of re reaction (c) (c) Heat Heat of comb combus usti tion on (d) (d) Heat Heat of solu soluti tion on 42. The heats of combustion of rhombic and monoclin monoclinic ic sulphur sulphur are respec respective tively ly F0E0 F0E0 and F10;0 calories9 .hat 'ill be the heat of conversion of rhombic sulphur to monoclinic (a) F0E0 ca calories (c) A F0 calories
(b) F10;0 ca calories (d) N F0 calories
H 2O(l) is A D90 cal& cal&
43. The heat of formation of
the heat of of formation formation of H 2O(g) is li,ely to be (a) (a) A D9 D90 0 cal (b) (b) A F9 F9I I cal (c) (c) D090 cal (d) (d) A 5D9 5D9; ; cal 44. .hich of the follo'ing fuels 'ill have the highest caloric value (!0g (!0g)) (a) Charcoal (b) Gerosene (c) .ood (d) 7ung 45. The heat of combustion of carbon is AEI cal at 1 atm pressure9 atm pressure9 The intrinsic energy of CO 2 is (a)
+EIcal
(b)
− EIcal
(c)
+IFcal
(d)
−IFcal
46. The heat of neutralisation of a strong acid and a
strong
al,ali
is
−1
5F90! mol mol
mol release released d 'hen 'hen 095mol
mi"ed 'ith 092mole of
47.
(a) CaCO; → CaO+ CO2
9
The
heat
of HNO; solution is
KOH is
(a) 5F90!
(b) 119I !
(c) 2D95!
(d) ;I9E!
KOH and solution of 500ml of 092 2 KOH 500ml of 092 2 HCl is mi"ed mi"ed and stirred stirred==
the rise in temperature is T 1 9 The e"periment is repe repeat ated ed usin using g 250ml each each of soluti solution& on& the
(b) 5e + S → 5eS (c) NaOH + HCl → NaCl + H 2O
temperature raised is T 2 9 .hich of the follo'ing
(d) CH I + 2O2 → CO2 + 2H 2O
is true
!n the reaction =
D0!
∆H is ,no'n as
39.
O2
41. The heat change change ∆H for the reaction
A EI90& A D9I and A 1F9E cal
CO 2(g) + H 2(g) → CO(g) + H 2O(g)=∆H
2
(a) Heat of reaction (b) Heat of formation (c) (c) Heat Heat of of vapo vapori risa sati tion on (d) (d) *one *one of the the abov above e
respectively9 The heat of combustion of methane is (a) (a) A 2129 2129E E cal (b) (b) A 1;9 1;9D D cal (c) (c) A ;0I ;0I9; 9; cal (d) (d) A 1059 10592 2 cal 33. The heat of of reaction does does not depend depend upon (a) Temperature emperature of the reaction reaction (b) -hysical state of reactants reactants and products products (c) .hether .hether the the reaction reaction is carried carried out at constan constantt pressure or at constant volume (d) The method method by 'hich 'hich the nal nal produ products cts are obtained from the reactants 34. Heat of neutralisation of a strong acid by a strong base is a constant value because (a) 3alt formed formed does does not hydro hydrolyse lyse
38.
1
(a) Heat of for formatio ation n (b) (b) Heat Heat of comb ombustio stion n (c) Heat of of ne neutrali/ation (d) Heat of of re reaction Heat of combustion of a substance (a) !s al'ays al'ays posi positiv tive e (b) !s al'ays al'ays negativ negative e (c) !s eual eual to heat heat of forma formation tion (d) *othing can be said 'ithout 'ithout reaction reaction
48.
49.
(a) T 1 = T 2
(b) T 1 = 2T 2
(c) T 1 = IT 2
(d) T 2 = ET 1
$nthalpy of a compound is eual to its (a) (a) Heat Heat of of comb combus usti tion on (b) (b) Heat Heat of of for formati mation on (c) Heat of re reaction (d) Heat of of so solution (e) (e) Heat Heat of dilu dilutio tion n .hich is the best denition of >heat of neutrali/ation? (a) The heat heat set set free free 'hen 'hen one gram molecule molecule of of a base is neutrali/ed neutrali/ed by one gram gram molecule of
Thermodynamics and Thermochemistry Thermochemistry 169 Thermodynamics
an acid in dilute solution at a stated temperature (b) The heat heat absorbed 'hen one one gram molecule molecule of of an acid is is neutrali/ed neutrali/ed by one one gram molecule of a base ase in dilu ilute solu olution tion at a stat state ed temperature (c) The heat heat set free free or absorbed absorbed 'hen 'hen one gram atom of an acid is neutrali/ed by one gram atom of a base at a stated temperature (d) The heat heat set free or absorbe absorbed d 'hen a normal normal solution containing one gram euivalent of an acid acid is neut neutra rali li/e /ed d by a nor normal mal solu soluti tion on containing one gram euivalent of a base at a stated temperature (e) The heat heat set free free 'hen 'hen one gram gram euivalent euivalent of an acid is neutrali/ed by one gram euivalent of a base ase in dilu ilute solu olution tion at a stat state ed temperature 50. The compound compound 'ith negative negative heat of formation formation are ,no'n as (a) $ndothe $ndothermic rmic compound compound (b) $"othe $"othermic rmic compound compound (c) Heat of format formation ion compo compound und (d) *one *one of the the above above 51.
!f H + + OH − → H 2O + 1;9Fcal& then the heat
(d) ever eversib sible le or irriv irriver ersib sible le and and endo endoth ther ermic mic or e"othermic 56. The heat of formation is the change in enthalpy
accompanying the formation of a substance from its element elements s at 2ED K and 1 atm pressure9 3ince the enthalpies of elements are ta,en to be /ero& the heat of formation (∆H ) of compounds (a) (b) (c) (d) (d)
57. The heat of combustion of
58.
59.
60.
and
The heat of formation of
(a)
− I90cal
(b)
+I0cal
(c)
−D0ca
(d)
+D0cal
!f a chem chemic ical al reac reacti tion on is acco accomp mpan anie ied d by the the evolution of heat& it is (a) Catalytic (b) -hotochemical (c) $ndothermic (d) $"othermic reaction that ta,es place 'ith the absorption of energy is (a) (a) 4urn 4urnin ing g of of a can candl dle e (b) (b) usti usting ng of iron iron (c) (c) $lec $lectr trol olys ysis is of of 'ate 'aterr (d) (d) 7ige 7igest stio ion n of food food .hich of the follo'ing is an endothermic reaction (a) 2H 2 + O2 → 2H 2O (b) N2 + O2 → 2NO
(d) ;O2 + C 2 H 5OH → 2CO2 + ;H 2O 61.
+ CH ;COOH (d) NaOH Heat Heat of neut neutra rali lisa sati tion on for for the the give given n reac reacti tion on −1 NaOH + HCl → NaCl + H 2O is 5F91! mol mol 9 .hat 'ill be the heat released 'hen 0925mole of titrat ated ed agai agains nstt NaOH is titr 0925mole of HCl (a) 2295! mol−1
mol−1 (b) 5F91! mol
(c) 1I9;! mol−1
mol−1 (d) 2D9H! mol
62.
eaction& H 2(g) + I 2(g) → 2HI (g) ∆H = −129I0 cal9 ccording to this& the heat
of formation of HI 'ill HI 'ill be (a) 129I cal (b) (b) A 129 129I I cal (c) (c) A 920 920 cal (d) (d) 920 920 cal ll reactions 'ith chemical dissociation are
63.
8ne of the phenomena phenomena 'hich cannot be described as combustion is (a) 8"idation 8"idation of coal coal in in air (b) 4urning 4urning of magnesium magnesium in nitroge nitrogen n (c) eactio eaction n of antimony antimony in chlori chlorine ne (d) ighting ighting of an elect electric ric lamp .hich of the follo'ing statements is correct about heat of combustion (a) (a) !t may may be e"othe otherrmic mic in some some case cases s and and endothermic in other cases (b) !t is applicable applicable to gaseous gaseous substances substances only only (c) !t is al'ays al'ays an e"othe e"othermic rmic reacti reaction on (d) !ts value does not change 'ith 'ith temperature temperature
H2 +
(b) evers eversible ible and endother endothermic mic
1 O2 2
→
H 2O=∆H
= −HD9;Ecal
K + H 2O + .ater →
KOH (aq) +
(a) evers eversibl ible e (c) (c) $"ot $"othe herm rmic ic
20cal & − I0cal
(c) 2NaOH + H 2SOI → Na2SOI + 2H 2O
(c) NH I OH + HCl
55.
CH I(g) & C(graphite )
methane is
(b) CH ;COOH + NH I OH
54.
ar are
− 10cal respectively9
(a) HCl HC l + NaOH
53.
H 2( g)
and
of neutrali/ation for complete neutrali/ation of one mole of H 2SOI by base 'ill be (a) 1;9F cal (b) (b) 2F9I 2F9I cal (c) 9D5 9D5 cal (d) (d) ;9I2 ;9I25 5 cal 52. The lo'est value of heat of neutrali/ation neutrali/ation is obtained for
!s al'ays al'ays negative negative !s al'ays al'ays posi positiv tive e ay be be negati negative ve or positive positive !s /er /ero
KOH
1 2
H 2=∆H
= −IDcal
KOH (aq)=∆H = −1Ical + .ater → KOH
Thermodynamics Thermodynamics and Thermochemistry 170
The heat of of formation of
64.
71. The
cal) KOH is (in cal)
(a) −HD9;E+ ID− 1I
(b) −HD9;E− ID + 1I
(c) HD9;E− ID+ 1I
(d) D9;E D9;E N ID N 1I
di+erence di+erence bet'een bet'een heats of reaction at constant pressure and at constant volume for the reaction
2C H H H (l) + 15O2(g) → 12CO 2(g) + HH 2O(l) at 25o C in ! is (a) AF AF9I; (c) A; A;9F2
.hich .hich of the follo'in follo'ing g react reaction ion can can be used used to dene the heat of formation of CO 2 (g) + O 2(g) = CO 2(g) (a) C(graphite)
72.
(b) CH I (g) + 2O2(g) = CO 2 (g) + 2H 2O(l) (c) CO(g) +
65. The
enthalpy
90! − IH
1
of
mol mol
C
(graphite)
CO2(g)=∆H
95 = −;E;
!
formation of ammonia is 9 The enthalpy change for the
(a)
− 195!
(b)
+ 195 !
(c)
+
;90!
(d)
−;90!
73.
(b) E290 (b) E290 ! mol−1
(c) (c) A 2;90 2;90 ! mol−1 (d) (d) A E29 E290 0 ! mol−1 66. The heat of combustion of ben/ene determined determined in 1 mol− DF0calmol a bomb calo alorime rimetter is − DF0 at
25o C 9 The value of
74.
∆E for the reaction is
(a)
−1FI0 cal
(b)
−DF0 ca
(c)
cal −DF2
(d)
−DFIca
.hich of the follo'ing values of heat of formation indicates that the product is least stable (a)
−EIcal
(b)
9Hcal − 2;1
(c)
+219I cal
(d)
+ HI9D cal
.hic .hich h of repr repres esen ents ts
the the the the
foll follo' o'in ing g stan standa dard rd
euat uatio ions ns cor correct rectly ly heat heat of form format atio ion n
(∆H o 3 ) of methane
)+ 2H 2(g) = CH I (g) (a) C(d/amond ) + 2H 2(g) = CH I (l) (b) C(gra-./te
67. The formation of 'ater from H 2 (g) and O2 (g)
is an e"othermic reaction because
) + 2H 2(g) = CH I (g) (c) C(gra-./te
(a) The che chemic mical al ener energy gy of H 2(g) and O2 (g)
) + IH = CH I (g) (d) C(gra-./te
is more than that of 'ater
75.
(b) The che chemic mical al energ energy y of H 2(g) and O2 (g) is less than that of 'ater (c) *ot depe depende ndent nt on energy energy more than that of 'ater !n the reaction for the transition of carbon in the diamon diamond d form form to carbo carbon n in the the graph graphite ite form& form& 95 cal9 This points out that ∆H is − I5; Jraphite is chemically chemically di+erent di+erent from diamond diamond Jraphite Jraphite is as stable stable as diamon diamond d Jraphite Jraphite is more stable stable than diamond diamond 7iamond 7iamond is more stable stable than than graphite graphite
(b)
H 2(g) +
(a) 1090 (c) A 1290
H (aq9) + OH − (aq9) → 2H 2O(l)=∆H (d) C 2H 2(g) + 2
= −1;9Fcal
1 O2(g) → 2CO 2(g) + H 2O(l) 2
= 76.
6alues of heats of formation for S/O2 and 2gO are −ID9I an and
−1
mol
of
−;I9F!
respectively9 The
heat of the reaction 22g + S/O2 → 22gO+ S/ is (a) 2191H! (c) 77.
(b) A 90 (d) A 1I90
= −5Dcal
(c)
N 2OI (g) are D90 and 290 respectively9 The heat of dimeri/ation of NO2 in
ca 2NO2(g) = N 2OI (g)
1 O 2(g) → H 2O(l)=∆H 2
+
NO2(g) an and is
= −11Hcal
∆H = −;10cal
!n the combustion of hydrocarbons& hydrocarbons& ∆H is (a) *egative (b) e ero (c) -ositive (d) ndeterminate
70. The standard heats of formation in cal
!n 'hich of the follo'ing reactions does the heat change represent the heat of formation of 'ater (a)
2H 2(g) + O2(g) → 2H 2O(l)=∆H
(d) (d) The The tempe tempera ratu ture re of H 2(g) an and O2 (g) is
(a) (b) (c) (d)
= −;E5
#rom the data& the ∆H 'hen diamond is formed from graphite& is
(a) I90 ! mol−1
69.
CO 2(g)=∆H
+O2(g) →
reaction 2NH ;(g) → 2N 2(g) + ;H 2(g) is
68.
+ C 2(g) →
O2(g) = HCO 2 + ;H 2O(l)
2
−1
(diamond)
!
1 O2(g) = CO 2(g) 2
(d) C H H H (l) + F
C
(b) N ;9F2 (d) N F9I;
−1;9H2!
(b)
−21910!
(d) 1;9H!
4ased on the follo'ing thermochemical thermochemical euations
H 2O(g) + C(') → CO(g) + H 2(g)=∆H
= 1;1 1;1!
Thermodynamics and Thermochemistry Thermochemistry 171 Thermodynamics
CO(g) +
1 O2(g) → CO 2(g)=∆H 2
H 2(g) +
1 O2(g) → H 2O(g)=∆H 2
C(') + O2(g) → CO2(g)=∆H The value of
78.
79.
85.
% is
(a)
−;E; !
(b)
− H55!
(c)
+ ;E; !
(d)
H55! +H55
! − 1I12
(d)
92! − 1I1
Carbon and carbon mono"ide burn in o"ygen to form carbon dio"ide dio"ide according according to the follo'ing follo'ing reactions →
2CO + O2
CO 2=∆H
= −;EI!
→
2CO 2=∆H
The heat of mono"ide is thus
formation
86.
(a)
−
(c)
90! − 1F5
mol−1
= −5HE!
mol−1
1mol of
of
−1
(b)
10E 95! − 10E
1
(d)
95! − DF
21E 21E 90! mol
mol mol−
carb carbon on mol mol−1
→
2HCl + IIcal is
(a) II cal (b) (b) II00 II000 0 cal (c) 22 cal (d) 11 cal .hen 'ater is added to uic, lime& the reaction is
(b) ore ore than in the the second second case by by 19DE!
(c) $"plosive
(d) *one of these
#or an e"othermic reaction products cts is less than than H of the H of the produ
(b) reactants
products is more than than H of the H of the products
(c) reactants
product cts s is eual eual to H of the H of the produ
88.
!n an e"othermic reaction ∆H is (a) -ositive
(b) *egative
(c) ero negative 89. The
heat
(d) 4o 4oth change
for
the
positive
or
follo'ing reaction
C(') + 2S(') → CS 2(l) is ,no'n as (a) (a) Heat Heat of of vapo vapori ri/a /ati tion on (b) (b) Heat Heat of of solu soluti tion on (c) Heat of fusion
(d) Heat of formation
90. The enthalpy of combustion of ben/ene ben/ene from the
follo'ing data 'ill be
(d) ∆H is al'ays positive
(i)
81. The energy evolved is highest for 'hich of the
follo'ing reactions (a) 5 + e−
→ −
(c) S + 2e !n
1
mol mol−
Heat of formation in the reaction
H 2 + Cl2
87.
mol mol−1
(b) $ndothermic
(a) reactants
the
5 −1
→
S
(b) Cl + e−
2−
combustion
→
(d) O + 2e → O 290 gm
2−
H 2(g) +
of metha methane ne
200cal (b) 200
;00cal (c) ;00
I00cal (d) I00
1 O2(g) → H 2O(l)=∆H 2
9E! = −2D5
(iii) C(') + O2 (g) → CO 2 (g)=∆H = −;E;95!
is liberated& heat of combustion of methane 'ould be 100cal (a) 100
= +I59E!
(ii)
Cl −
−
of
HC(') + ;H 2(g) → C H H H (l)=∆H
25cal heat
84.
mol mol−1
mol mol−1
(b)
(a) $"othermic
(d) ore ore than in the the second second case by by 09EI5!
83.
respectively& the
(a) ess ess than in in the second second case case by 19DE! (c) ess ess than in in the second second case case by 119;I!
82.
+ 1I1 1I1 92!
C + O2
Heat of transition is the heat evolved or absorbed 'hen a substance is converted from (a) 3olid 3olid to to liu liuid id (b) 3olid 3olid to to vapour vapour (c) iuid iuid to vapo vapour ur (d) 8ne allotropic allotropic form form to another allotropic form #or the allotropic change represented by euation C(d/amond ) → C(gra-./t ) = the enthalpy chang change e is ∆H = −19DE! 9 !f H g of diamond
−1
2DH 2DH! mol
(a) + 1I12! mol−1 (c)
= % !
−
enthalpy of combustion of C 2 H I (g) 'ill be
= −2I2!
and H g of graphite are separately burnt to yield carbon dio"ide& the heat liberated in the rst case is
80.
52& A ;EI and
= −2D2!
(a) (a) N ;1F ;1F29 29D D !
(b) (b) A 15I 15IE9 E92 2 !
(c) (c) A ;1F2 ;1F29D 9D !
(d) (d) A ;2 ;2I9 I9 !
Complete combustion of CH I gives
$nth $nthal alpy py of form format atio ion n of H5 an and HCl are − 1H1! and − E2! respectively9 .hich of the follo'ing statements is incorrect
(a) CO2 + H 2O
(b) CO2 + H 2
(a) HCl is more stable than
(c) COCl 2
(d) CO + CO2 + H 2O
(b)
!f enthalpies of formation of
C 2 H I (g)&CO 2(g)
and H 2O(l) at 25o C and 1at
pressure be
91.
H5
H5 and HCl are e"othermic compounds
(c) The anity anity of Quorine Quorine to hydrogen hydrogen is greater greater than the anity of chlorine to hydrogen (d)
H5 is more stable than HCl
Thermodynamics Thermodynamics and Thermochemistry 172 92. The heat of reaction at constant pressure pressure is given
by
93.
94.
SO;
−200!
(b)
−;5H 92!
(c) H P − H R
(d) H R − H P
(c)
+200!
(d)
−;EH 92!
!n an endothermic reaction& the value of ∆H is (a) e ero
(b) -o -ositive
(c) *egative
(d) Constant
29201Hg
of
ace acetalde aldehy hyd de
produce uced
of heat on comb combu ustio stion n in
(a) 2FE cal cal
(b (b) EF2 cal
(c) 2F9E cal
(d) (d) 29FE 29FE cal
C+
1 O2 2
→
1 O2 2
CO= ∆H
O2 9
→
CO2 =∆H
(c)
CI HEOH(l) & if
(b)
∆H is enthalpy of combustion
and and ∆E is the heat of combustion at constant volume& then (a) ∆H < ∆E (b) ∆H = ∆E (c) ∆H > ∆E ∆ H & ∆E
→
relation cannot be predicted
CO2=∆H
O2
→
=
%
CO2= ∆H
=
6
99. The values of heat of formation of
mol mol
1
mol mol− (d)
mol mol−1
(b) $"othermic (d) eversible
CH I is completely burnt in air9 The
∆E at
cal9 The value of ∆H for 2Fo C is 1E90 cal9
the reaction 'ould be (R = 290 calK −1mol−1) (a) (a) 209D cal (c) (c) 1D9D cal 104. The
(b) (b) 1E9D 1E9D cal (d) (d) 2092 2092 cal
enthalpy of solution of
)aCl292H 2O(') −1
D9D ! mol mol
)aCl2(') and −209H
ar are
and
respectively9 The enthalpy change
for the reaction )aCl2(') + 2H 2O → is (a) (a) 2E9I ! (b) (b) A 119 119D D ! (c) (c) A 209 209 ! (d) (d) A 2E9 2E9I I ! 105. The enthalpy change of a reaction does not depend on (a) The state state of reactant reactants s and products products (b) *ature *ature of reactants reactants and produc products ts (c) 7i+eren 7i+erentt intermedia intermediate te reaction reaction (d) !nitial and nal enthalpy enthalpy change change of a reaction
; 2
O2 → SO; + 2 + cal
1 2
O2 → SO; + 1 cal
#ind out the heat of formation of SO2
SO2 and
an and −ED92! 9 The The heat of reaction of the follo'ing reaction 'ill be 92! −2ED
(b)
−1
+ 12D 12D 902!
SO2 +
CO is (b) 6 − 2% (d) 2 % − 6
(c) % + 6
mol mol−1
number of moles of 'ater produced are (a) 095 (b) 1 (c) 2 (d) 1D 103. #or the reaction *(g) + 2)(g) → 2C(g) + ;((g) & the the valu value e of
106. S +
Then the heat of formation formation of (a) % − 6
;E; 9;& − 2E; 2E; 9F2 −;E;
mol mol−1 respectively
(a) $ndothermic (c) !sotemperature
(d) The standar standard d molar enthalpy enthalpy of combustion combustion of carbon (graphite) !n the complete combustion of butanol
SO; ar are
12D 902! − 12D
(') and
101. #ermentation is a reaction called
3tandard molar enthalpy of formation of CO 2 is eual to (a) er ero (b) The standar standard d molar enthalpy enthalpy of combustion combustion of gaseous carbon (c) (c) The The sum sum of stan standa darrd mola molarr entha nthalp lpie ies s of formation of CO and O2
2
9FH! − 110D
102. D gm of
(d) (d) A !
CO +
and
+ 12 9D02 D02!
= −2I!
(c) N 1 !
1
carbon carbon disulphide disulphide (l) are are
(a)
= −I2!
A 1 !
C + O2
disulphi disulphide de (l) & given that the standard heat of
− 129D02 !
(a) N !
(d)
100. Calculate the standard heat of formation of carbon
comb combus usti tion on of carb carbon on (') & sulph ulphu ur
The heat of of formation of CO 2 is
98.
→
(a)
CO +
97.
O2
(b) E R − E P
Calculate the heat of combustion of CH ;CHO
96.
2
(a) E P − E R
1;9E5cal
95.
1
SO2 +
(a) 2 + − 1
(b) 2 + + 1
(c) + + 1
(d) 2 + 1
107. The combustion enthalpies enthalpies of carbon& hydrogen hydrogen
and
methane
are
−
−1
mol ;E5 95! mol
&
Thermodynamics and Thermochemistry Thermochemistry 173 Thermodynamics −
−1
mol 2D5 2D5 9D ! mol
an and
−
−1
mol DE0 DE0 9I ! mol
114. Calculate the heat of formation of
the follo'ing data
resp respec ecti tive vely ly at 25o C 9 The The valu value e of stan standa dard rd for format mation ion enthal thalp pies ies of metha thane at that hat temperature is (a)
2P (') + ;Cl 2(g) → 2PCl ; (l)=∆H
PCl ; (l) + Cl 2 (g) → PCl 5 (')= ∆H
−1
(a) (a) A 10D9 10D9F F cal (c) (c) A 1DI 1DI9 9 cal
DE0 DE0 9I ! mol mol
(b) −
(c)
− FI9F!
mol mol−1
(d)
−1
mol 2ED 2ED 9D ! mol
10F 9F! − 10F
115. .hen
50cm
mol mol−1
(c) (c)
(d)
109. The neutralisation of a strong acid by a strong
base liberates an amount of energy per mole of H + that (a) 7epends upon 'hic hich acid acid and and base ase are are involved (b) 7epe 7epend nds s upon upon the temper temperatu ature re at 'hich 'hich the reaction ta,es place (c) 7epend 7epends s upon 'hich 'hich catalyst catalyst is used used (d) !s al'a al'ays ys the the same same 110. .hen 095g of sulphur is burnt to SO2& I9H !
of heat heat is libe libera rate ted9 d9 .hat .hat is the the enth enthal alpy py of formation of sulphur dio"ide (a) (a) N 1IF9 1IF92 2 ! (b) (b) A 1IF9 1IF92 2 ! (c) (c) A 2EI 2EI9I 9I ! (d) (d) N 2EI9 2EI9I I ! 111. 8/on 8/one e is prep prepar ared ed by pass passin ing g sile silent nt elec electr tric ic discharge through o"ygen9 !n this reaction (a) $nergy $nergy is given given out (b) $nergy $nergy is absor absorbed bed (c) 8"ygen 8"ygen is loaded loaded 'ith 'ith energ energy y (d) 8"ygen 8"ygen is dissocia dissociated ted into into atoms 112. Combusti Combustion on of glucose glucose ta,es ta,es place place accordin according g to the euation&
CH H 12OH
+
HO2
→
HCO2
+
HH 2O &
∆H = −F2cal9
Ho' much energy 'ill be reu reuire ired d for the produ product ction ion of 19 g of glucose (olecular mass of glucose K 1D0 g) (a) (a) 090 090I I cal (b) (b) 09I 09I cal (c) 9I cal (d) I cal 113. Jiven that
C(') + O2(g) → CO 2(g)&∆H
;EI! = −;EI
2H 2(g) + O 2(g) → 2H 2O(l)&∆H
=
5HD!
CH I (g) + 2O2(g) → CO 2(g) + 2H 2O(l)
(b) (b) N 10D9 10D9F F cal (d) (d) N 1DI9 1DI9 cal of a str strong ong acid acid is adde added d to
of an al,ali al,ali&& the tempera temperatur ture e rises rises by
116.
(a) 5o C
(b) 10o C
(c) 25o C
(d) 20o C
H 2(g) +
1 O2(g) 2
→
H 2O(l) =
K A 2D59D ! ∆H at 2ED K K The molar enthalpy of vaporisation of 'ater at 1 atm and atm and 25o C is II !9 !9 The standard enthalpy of formation of 1 mole of mole of 'ater vapour at 25o C is (a) (a) A 2I19 2I19D D ! (b) (b) 2I19 2I19D D ! (c) (c) ;2E9D E9D ! (d) (d) A;2E A;2E9D 9D ! 117. .hen I g of iron is burnt to ferric o"ide at constant pressure& 2E92D ! of ! of heat is evolved9 .hat is the enthalpy of formation of ferric o"ide (t9 .t9 of 5e K 5) (a) A D19ED D19ED ! (b) (b) A D1E9 D1E9D D ! (c) (c) A I09 I09EE EE ! (d) (d) N D1E9 D1E9D D ! 118. .hen a strong acid& strong base or their salt are dissolved in 'ater& they are completely ionised9 !f a strong acid is added to a strong base& H + ions from the former combine combine 'ith OH − ions of the latter forming 'ater9 The formation of each 'ater molecule molecule liberates liberates a certain certain uantity uantity of energy energy and the reaction is e"othermic9 The heat liberated 'hen one mole of 'ater is formed by combining hydrochl hydrochloric oric acid and sodium sodium hydro hydro"ide "ide is 1;9F cal9 cal9 The heat liberated 'hen one mole of 'ater is formed by combining sulphuric acid and sodium hydro"ide is (a) (a) 2595 cal
(b) (b) D95 D95 cal
(c) (c) 1;9F cal
(d) ;I cal
119. 291 g of 5e combines 5e combines 'ith S evolving ;9FF !9 !9 The
heat of formation of 5eS in 5eS in ! !mol is mol is (a) A 19FE
(b) A 10095
(c) A ;9FF
(d) *one of these
120. !n
H2
the +
Cl 2 → 2HCl& ∆H
=
1EI! 9
reactionB Heat of
formation of HCl is
∆H = −DE2!
Heat of formation of CH I is [DCE 1999]
(a) A F0 ! (c) A 2II !
= −;29D cal
temperature rise 'ould be
+ ess ess than than +
(b) (b) $ua $uall to
9D cal = −151
; 5o C 9 !f 250cm of each liuid are mi"ed& the
hydro"ide are mi"ed9 !f + is the heat of formation of 'ater& then heat evolved on neutralisation is
+ T'ice 'ice of +
;
50cm ;
108. $ual $ual volume volumes s of methan methanoic oic acid acid and sodium sodium
(a) (a) ore ore tha than n
PCl 5 (') from
(b) (b) F19D F19D ! (d) (d) N FD2 FD2 !
(a) N EF EF !
(b) (b) N 1EI 1EI !
(c) (c) A 1EI !
(d) (d) A EF !
121. $nth $nthal alpy py
of neut neutra rali lisa sati tion on of ace acetic tic acid acid by mol9 and and the the heat heat of NaOH is −509H! mol neutralisation of a strong acid 'ith a strong base
Thermodynamics Thermodynamics and Thermochemistry 174
is A 559E ! !mol9 mol9 .hat is the value of ∆H for the
(a) HNO; (∆H = −;;) (b)
ionisation of CH ;COOH
KCl (∆H
(a) N 59; 59; ! !mol
(b) (b) N 92 92 ! !mol
(c) N D92 ! !mol
(d) (d) N E9; E9; ! !mol
(c) NH I NO; (∆H = +2595)
C + 2S → CS 2
128. !n the reaction
5F9;2 ! for ! for
; + &/OH (a) HNO
(b) HCOOH + KOH KOH
(c) HCl + NH I OH
(d)
+
(d)
HCl (∆H = −FI91)
122. Heat of neutrali/ation of the acidLbase reaction is
CH ;COOH
= +1F9HI)
+ ∆ H & ∆H is the
(a) (a) Heat Heat of com combu bust stio ion n (b) (b) Heat Heat of of neut neutra rali lisa sati tion on (c) Heat of solution (d) *one of these 129. The heat of formation of methane
NaOH
C(') + 2H 2 (g)→ CH I (g) at constant pressure
123. The heat change for the follo'ing reaction at 2EDo K and at constant pressure is +F9;cal
is 1D50 1D500 0 cal at 25o C 9 The heat of reaction at constant volume 'ould be (a) (a) 1FE0 1FE0I I cal (b) (b) 1D20 1D202 2 cal (c) (c) 1DFED FED cal (d) (d) 1E0E 1E0E cal
*2 )(')→ 2 *(') + 1 2 )2 (g) & ∆H = +F9; cal
130. The enthalpy enthalpy of combustion of
The heat change change at constant constant volume 'ould be (a) F9; cal
A
;250 !9 !9 .hen 09;E g of ben/ene is burnt e"cess of o"ygen in an open vessel& the amount of heat evolved is
(b) ore ore than than F9; F9;
(c) ero
C H H H(l ) is
(d) *o *one of these
124. The heat evolved in the combustion of ben/ene is
given by the euation
CHH H(l) + F
1 2
O2(g)
→
(a) (a) 192 1925 5 ! (c) (c) ;295 ! 95 !
;H 2O(l) + HCO2(g)
131.
C(') + O2(g)→ CO 2=
−1
∆H = FD190 cal mol
CO(g) +
.hich of the follo'ing uantities of heat energy 'ill be evolved 'hen ;E g of ben/ene is burnt in an open container (a) 122925 122925 cal mol−1 (b) (b) ;E09 ;E095 5 cal mol−1
H 2(g) + Cl 2(g) → 2HCl (g)9 ∆H
= −IIcal
2Na(') + 2HCl (g) → 2NaCl(') + H 2(g)& ∆H = −152cal
Na(') +
(b) (b) A 1E 1E cal
(c) A ED cal
(d) 5I cal A1
are are A ;E; ;E;95& 95& A11 A11095 095 and and A 2I1 2I19D!mol 9D!mol respective respectively ly99 The standard standard enthalpy enthalpy change (in !) !) the
reaction
CO2(g) + H 2(g) →
CO(g) + H 2O(g) is (a) 52I91 (c) A 2295
+
% +
o 126. The ∆H 3 for CO2 (g)&CO(g) and H 2 O(g)
for
O 2 (g)→ CO 2 =
∆H =
1;592cal (a)
HCl and NaOH is (a ( a) ero (b) A 5F9; ! (c) (c) N 5F 5F9; ! (d) *one *one of of thes these e 133. The follo'ing thermochemical thermochemical reactions reactions are given
=
(a) A 10D 10D cal
2
Then heat heat of formation of CO(g) is A 29I cal (b) (b) I192 I192 cal (c) (c) 29I cal (d) (d) A 22E9 22E92 2 cal
2
#or the reaction
1 Cl 2 (g) → NaCl(')&∆H 2
1
∆H = −EIcal
132. The heat of of neutrali/ation of
(c) (c) 152 15290 90 cal mol−1 (d) (d) 5D9 5D9F5 F5 cal mol−1 125.
(b) (b) 192 1925 5 ! (d) (d) ;295 ;295 !
(b) I192 (d) A I192
127. .hich of the follo'ing compounds 'ill absorb the
ma"imum uantity of heat 'hen dissolved in the same amount of 'ater : The heats of solution of these these compoun compounds ds at 25o C in ! !mole mole of each solute is given in brac,ets
1 O2 2 1 O2 2
→
→
2O + ;519I ! %O + E09D !
!t follo's that the heat of reaction for the follo'ing process 2 + %O %O < 2O + % is given by [AMU 2001]
(a) (a) I229 I2292 2 ! (b) (b) 2D9 2D9F F ! (c) (c) A II2 II292 92 ! (d) (d) 209 209 ! 134. !f the the heat heat of combu combust stion ion of carbo carbon n mono" mono"id ide e at o constan constantt volume volume and a nd at 1F C is A 2D;9; 2D;9; !& !& then its heat heat of combusti combustion on at consta constant nt pressu pressure re L1 −1 (R = D9;1I ! degree mol ) (a) (a) A 2DI9 2DI95 5 ! (c) (c) ;DI95 I95 !
(b) (b) 2DI9 2DI95 5 ! (d) (d) A ;DI9 ;DI95 5 !
135. Heat Heat of format formation ion of
and
H 2O 2 is
H 2O is
−1DD! mole
9 The enthalpy −2DH! mole enthalpy
Thermodynamics and Thermochemistry Thermochemistry 175 Thermodynamics
change for the reaction 2H 2O2 → 2H 2O + O2 is (a) 1E ! (c) EDI !
(b) (b) A 1E 1E ! (d) (d) A EDI EDI !
136. The values of ∆H for the combustion of ethene
and ethyne are A ;I191 and A ;1090 cal respectively9 .hich of the follo'ing is a better fuel (a) C 2 H 2
(b) C 2 H I
(c) 4oth of these (d) *one of these 137. #or e"othermic reaction& the euilibrium constant (a) !ncreases !ncreases 'ith increase increase of P (b) 7ecrea 7ecreases ses 'ith 'ith increase increase of P (c) !ncrease !ncreases s 'ith increase increase of temperatu temperature re (d) 7ecreases 7ecreases 'ith increase of temperature temperature 138. !n order to decompose E g 'ater 1I295 ! ! heat is reuired9 Hence the enthalpy of formation of 'ater is (a) (a) A 1I29 1I295 5 ! (b) (b) N 1I29 1I295 5 ! (c) A 2D5 ! (d) (d) N 2D5 2D5 ! 139. .hat is ∆n for combustion of 1 mole of ben/ene& ben/ene&
'hen both the reactants and the products are gas at 2ED K (a ( a) 0 (b) ;2 (c) A ;2 (d) 12 140. !f
C + O2
H2
+
CH I
1 O2 2 +
CO2 + EI92 cal
→
→ H 2O +
2O2 → CO2
+
HD9;cal 2H 2O + 2109D cal
Then the possible heat heat of methane 'ill be (a) IF9; cal (b) (b) 2090 2090 cal (c) I59E cal (d) (d) A IF9 IF9; ; cal 141. Heat Heat of neut neutral rali/a i/atio tion n of strong strong acid acid and 'ea, 'ea, base is −1
144. .hen the aueous solution of 095 mole
HNO; is
mi"ed mi"ed 'ith the 09; mole of OH − solution& then 'hat 'hat 'ill 'ill be the the libe libera rate ted d heat heat ($nt ($ntha halp lpy y of neutrali/ation is K 5F91 !) !) (a) (a) 2D95 ! (b) (b) 1F91 1F91 ! (c) (c) I59F ! (d) (d) 19F 19F ! (e) (e) 29D5 9D5 ! 145. cylinder cylinder of gas is assumed assumed to contai contain n 1192 g of butane (C I H 10) 9 !f a normal family needs 20000 ! of ! of energy per day9 The cylinder 'ill lastB (Jiven that ∆H for combustion of butane is A 25D !) !) (a) 20 2 0 days (b) 25 2 5 days (c) 2 days (d) 2I 2 I days 146. Compounds 'ith high heat of formation are less stable because (a) High High tempe temperat ratur ure e is reu reuire ired d to synth synthesi esise se them (b) olecules olecules of such such compounds compounds are are distorted distorted (c) !t is dicu dicult lt to synthe synthesis sis them them (d) $nergy rich state state leads leads to instability 147. The heat evolved in the combustion of methane is given by the follo'ing euationsB
CH I (g) + 2O 2 (g)→ CO 2 (g) + H 2O(l)= ∆H = −DE09; !
Ho' many grams of methane 'ould be reuired to produce II5915 ! of ! of heat of combustion [AMU 2002]
(a) I g (c) 12 g
(b) D g (d) 1 g
148. Heats Heats of combusti combustion on (∆H o ) for
CH I (g)
and
−21;cal mol9 ∆H
o
C(')& H 2 (g)
−EI& − HD
ar are
respe respecti ctive vely ly99
and
The value value
of
for the reaction&
C(') + 2H 2 (g)→ CH I (g) is
mol (a) 5F91! mol
mol−1 (b) 1;9F! mol mol−1 (c) (c) ess ess tha than n 1;9Fcalmol mol−1 (d) ore ore than than 1;9Fcalmol
142. system is changed changed from state * * to state state ) by
one path and from ) to * to * another another path9 !f E1 and
E 2 are the correspo correspondin nding g changes changes in interna internall (a) E1 + E 2 = −,e + E 2 =
(b) (b) A 111 111 cal (d) (d) A 1F0 1F0 cal
149. !f the value of ∆H in a reaction is positive& then
the reaction is called (a) $"othermic (c) -olymorphic
(b) $ndothermic (d) -olytropic
150. $nthalpy of neutralisation of
NH IOH and HCl &
is numerically
energy& then
(c) E1
(a) A D5 D5 cal (c) A 1F cal
0
(b) E1 + E 2 = +,e
mol−1 (a) 5F91 ! mol
(d) *one *one of of thes these e
(c) > 5F91 ! mol−1
143. The heat evolved evolved during the the combination of of 2I g C
(b) < 5F91 ! mol−1 (d) (d) er ero
151. The heat of of neutralisation 'ill be highest highest in
and 12D g S follo'ing S follo'ing the change is
(a) NH I OH and CH ;COOH
C + S2
(b) NH I OH and HCl
→
(a) 11 cal (c) II cal
CS 2 = ∆H
=
2290 cal (b) ;2 cal (d) 22 cal
(c)
KOH and CH ;COOH
(d)
KOH and HCl
Thermodynamics Thermodynamics and Thermochemistry 176
H 2 molec molecule ule is heate heated d to high high
152. !f a m ol ole o f
(c)
temperature the follo'ing reaction ta,es place
CH I (g) + 2Cl 2(g)→ CH 2Cl 2(l) + 2HCl(g)
(a) H 2(g) + I;H! = H (g) + H (g)
(d) %e(g) + 25 2 (g) → %e5 I (g)
D20! = 2H 2(g) (b) H 2(g) + D20
159. $nthalpy change for a reaction does not depend
upon
(c) 2H 2 (g) + I;H ! = 2H 2 (d) H 2
+
H2
=
H+
+
(a) The physical states of reactants reactants and products
H+
153. .hich of the follo'ing reactions is not e"othermic
(a) C(') + O 2 (g)→ CO 2 (g)
(c) CH I (g) + 2O 2 (g)→ CO 2 (g) + 2H 2O(l)
1 2
O 2 (g) → CO 2 (g)
154. 8n combustion& combustion& carbon forms t'o o"ides o"ides CO and
CO 2 & Heat of formation of CO 2 gas is EI9; cal and that of CO is CO is 290 cal9 cal9 Heat of combustion of carbon is (a) 290 cal
(b) (b) A EI9 EI9; ; cal
(c) D9; cal
(d) (d) A 1209 1209; ; cal
155. 1 mole of con conc9 c9 HCl HCl reuir reuires es % moles moles of dilute dilute
NaOH for NaOH for neutralisation and 1 mole of mole of concentrate concentrate H 2SOI reuires 6 mole' 6 mole' of of small dilute NaOH then 'hich of the follo'ing reaction is true (a) 6 =
1 % 2
(b) % =
(c) % = 2 6
1 6 2
(d) *one *one of of thes these e
156. .hich of the reaction denes
o ∆H 3
(a) C(diamond ) + O 2 (g)→ CO 2(g)
1 1 H 2 (g) + 5 2 (g)→ H5 (g) (b) 2 2 (c) N 2 (g) + ;H 2 (g)→ 2NH ; (g) (d) CO(g) +
1 2
O 2 (g) → CO 2 (g) NH I NO; is decomposed in
a bomb bomb calo calori rime mete terr9 The The temp temper erat atur ure e of the the calorimeter increases by 912 K the the heat capacity of the system is 192; ! !gdeg. .hat deg. .hat is the molar heat of decomposition for NH I NO; (a) A F95; F95; ! !mol
(b) (b) A ;ED9 ;ED91 1 ! !mol
(c) (c) A 191 191 ! !mol
(d) (d) A 02 02 ! !mol
o
one one of the the foll follo' o'in ing g eua euati tion ons s is
∆H react eual
O2 → CO2 = ∆H = −;E59; ! mole 160. Cdi a N C gr + O2
→
CO 2 = ∆H
C gr → C dia= ∆H
9I ! = −;E;
mole
=
(a) A ;9D
(b) A 19E
(c) N ;9D
(d) N 19E
161. .hat is the 'eight of o"ygen that is reuired for
the complete combustion of 29D g of g of ethylene: (a) E9 g
(b) (b) E90 E90 g
(c) 9I g
(d) (d) 29D 29D g
comp omplete lete neutra utrali li/ /atio ation n of HCl 'ith NaOH& the heat of neutrali/ation is
162. #or
−1
(a)
+
mol 1;9F0! mol
(c)
−
mol 5F9;2! mol
−1
(b)
−
−1
mol 1;9F0! mol
(d) + 5F9;2! mol−1
163. The heat of combustion of carbon to −;E;95 ! mol9
The
heat
CO 2 is
released
upon
form format atio ion n of ;592 ;592 g of CO 2 from carbon carbon and o"ygen gas (a) + ;15!
(b)
− ;195 !
;15! −;15
(d)
95 ! +;1
(c)
164. .hic .hich h
of repr repres esen ents ts
the the the the
foll follo' o'in ing g stan standa dard rd
euat uatio ions ns cor correct rectly ly heat heat of form format atio ion n
(∆H o 3 ) of methane
157. 8ne gram sample of
158. #or 'hic 'hich h
(c) The nature nature of intermediate intermediate reaction steps (d) The di+eren di+erences ces in initial or nal temperatu temperatures res of involved substances
(b) C(') + 2S(')→ CS 2 (g)
(d) CO(g) +
(b) se of di+erent di+erent reactants reactants for the the same product product
o
to ∆H 3 for the product
(a) 2CO(g) + O 2 (g)→ 2CO 2 (g) (b) N 2 (g) + O; (g)→ N 2O; (g)
+IH (g) →
CH I (g)
(a)
C
(diamond)
(b)
C
(diamond)
+2H 2(g) →
CH I (g)
(c)
C
(graphite)
+2H 2(g) →
CH I (g)
(d)
C
(graphite)
+IH(g) →
165. !f the heat of formation of
CH I (g)
CO 2 is −;E;! 9 The
amount of heat evolved evolved in the formation formation of 0915 0915 ,g of CO 2 is (a)
−1;5F 9E
!
(b)
9E ! −12F5
(c)
90 ! −15F2
(d)
95 ! −11H5
166. .hich
of the follo'ing pairs neutralisation neutralisation eual to 1;9F Gcals (a) HCl & NH IOH
has
heat
(b) HNO;& KOH
of
Thermodynamics and Thermochemistry Thermochemistry 177 Thermodynamics
& CH ;COOH (c) NaOH
1 mol− ;00! mol (c) ;00
(d)
H 2SOI& NH IOH
2.
167. The enthalpies enthalpies
of combustion of carbon and carb carbon on mono monodi die e are are A;E; A;E;95 95 and and A2D; A2D; ! mol molA1 respectivley9 The enthalpy of formation of carbon mono"ide per mole is
(a)
95 ! −HFH
HFH 95 ! (b) HFH
95 ! (c) 110
3.
95 ! −110
(d)
168. The enthalpy of combustion combustion of methane at 25o C DE0! 9 The is DE0 The heat heat liberate liberated d 'hen 'hen ;92 g of
methane is burnt in air is (a) II5! (c)
4.
(b) 2FD! 1FD! (d) 1FD
DE0! −DE0
CO + 1 2O2 → CO2 & the the heat heats s of reac reactio tion n are are
5.
Q& − 12& − 10 respectively9 Then Q =
(a) A 2
(c) A 22 (d) A 1 170. Ho' much energy energy is relea release sed d 'hen 'hen mole mole of is
burnt
in
air
:
Jiven
o
∆H 3
6.
are A IE0&A 2I0 and N 10 !0mol (a) A 92 92 ! (b) (b) A ;F9 ;F9I I ! (c) (c) A ;595 ;595 ! (d) (d) A 209 2090 0 !
2g +
25e +
; O2 → 5e2O;& ∆H 2
1 O2 → 2gO& ∆H 2
= −1E;9I ! =
= −1I092!
→
7.
(b) (b) N1 N1D0 D02 2 !
(c) A D00 !
(d) (d) N 22D 22D !
172. The enthalpy enthalpy change
of
12 HCl
(∆H ) for the neutralisation
(c) A 22 cal cal (d (d) 22 cal The rst ioni/ation energy energy for &/ &/ is 59 59I eV and elec electr tron on ani anity ty of Cl is ;91 ;91eV 9 Th T he ∆H (in
(a) F0 (c) 1F0 Jiven
(b) 100 (d) 2F0 that = −1HH!
The bond energy energy C − H 'ill be (a) 20D ! !mole (b) (b) A I19 I19 ! !mole (c) D;2 ! !mole (d) *one *one of of thes these e 8.
by caustic potash in dilute solution
at 2ED 2EDK is
The H − H bond bond ener energy gy is I;0 ! mo l and −1 mol 9 ∆H for 2I0! mol Cl − Cl bond energy is 2I0
HCl is
−E0!
9 The The H − Cl bond energy is
(a) D !
(b) 5 !
about
(c) 5F9; !
(d) 50 !
1 mol− 1D0! mol (a) 1D0
1 mol− ;H0! mol (b) ;H0
mol−1 21;! mol (c) 21;
mol−1 I25! mol (d) I25
Bond energy 1.
(b (b) II cal
C(g) + IH (g)→ CH I (g)=∆H
;2gO+ 25e
(a) (a) A 1D0 1D02 2 !
(c) C ≡ N (d) N ≡ N The bond dissociation energies energies of gaseous H 2& Cl 2 a an nd HCl are are 10I& 10I& 5D and and 10; cal
!0mol) !0mol) for the reactio reaction n &/(g) + Cl(g) → &/ + + Cl − is (if resulting ions do not combine 'ith each other) (1eV = 19H × 10−1E ! )
.hat is the ∆H of the reaction
2g + 5e2O;
(b) C ≡ C
(a) A II II cal cal
for
CO2(g)& H 2O(g) and CDH1D(l) respectively
171. Jiven B
(a) 10I cal (b) (b) 109I 109I cal (c) (c) 10I0 cal (d) (d) 10I 10I cal The bond dissociation energy energy needed to form ben/ ben/yl yl radi radica call from from tolu toluen ene e is 9999 999999 than than the the formation of the methyl radical from methane (a) ess (b) uch (c) $ual (d) *one of the above .hich one of the follo'ing bonds has the highest average bond energy (cal ( calmol) mol)
respec respective tively ly99 The enthalpy enthalpy of formation formation of HCl gas 'ould be
(b) 2
octane
$ner $nergy gy reui reuire red d to dis dissoc sociat iate e I gm of gaseous gaseous hydrogen into free gaseous atoms is 20D ,cal at 25o C 9 The bond energy of H − H bond 'ill be
(a) S = O
169. !f ( i) i) C + O2 → CO2 & ( ii ii) C + 1 2O2 → CO & (iii) (iii)
1 mol− I00! mol (d) I00
9.
!f the bond dissociation dissociation energies energies of %6 & % 2 and
(a) (a) D0 calor/e' (c) 0 calor/e'
6 2 (all diatomic molecules) are in the ratio of 1 B 1 B 095 an and ∆ 3 H for the format formation ion of %6 is −1
− 200! mole
9 The bond dissociation energy
of % 2 'ill be 1 mol− 100! mol (a) 100
!f enthalp alpies ies of metha thane and and ethan thane e are are respectively ;20 and ;0 calories then the bond energy of C − C bond is
10.
!f the the bond bond energ energie ies s of H − H & )r − )r and mol−1 H)r are I;;& 1E2 and ;I ! mol respective ively&
1 mol− D00! mol (b) D00
(b) I0 calor/e' (d) (d) 120 120 calor/e'
the
∆H
o
for for
H 2(g) + )r 2(g) → 2H)r (g) is
the
react action ion&
Thermodynamics Thermodynamics and Thermochemistry 178
(a) N 2 21 ! (c) A 21 !
(b) (b) A 10; 10; ! (d) (d) N 10; 10; !
Free energy and Work function 1.
2.
3.
4.
5.
The free energy energy change change for a reversible reversible reaction reaction at euilibrium is (a) arge positive (b) 3mall negative (c) 3mall positive (d) 0 #or #or a spontane spontaneous ous change& change& free energy energy change change ∆G is (a) (a) -osit ositiv ive e (b) (b) *ega *egati tive ve (c) ero (d) Can be positi positive ve or negati negative ve minus sign of the free energy change denotes that (a) The reaction reaction tends to proceed proceed spontaneously spontaneously (b) The reactio reaction n is nonLspon nonLspontane taneous ous (c) The syste system m is in euil euilibriu ibrium m (d) The reaction reaction is very much unli,e unli,ely ly (b) ∆G = ∆H − T ∆S
(c) T ∆S − ∆G = ∆H
(d) ∆H = T ∆G + ∆S
t ;00 K & the the react reaction ions s 'hich 'hich have have follo' follo'ing ing valu values es of ther thermo mody dyna nami mic c para parame mete ters rs occu occurr spontaneously (a) ∆G
o
−1
o
−1
∆H
o
−1
= −200! mol
& ∆S o = I !K −1mol−1
mol−1 & ∆S o = I0 !K −1mol mol−1 (d) ∆H o = 200 ! mol 6.
7.
(b) #araday
(c) JibbsAHelmholt/
(d) Thomson
#or prec precip ipit itat atio ion n reac reacti tion on of
*g+
ions ions 'ith 'ith
11.
12.
9.
(c) Jibb%s Jibb%s free free energy energy
(d) *one of the above above
The dependence dependence of Jibbs free energy on pressure pressure for an isothermal process of an ideal gas is given by
09
occurs
∆G 'hen
pressure −ED00 cal
cal 5I0cal (a) 5I0
(b)
cal (c) ED00cal
(d) 0 cal
o
for the reaction % + 6 < 7 is is A I90 cal 9 The value of euilibrium constant of the reaction at 22Fo C is (R = 290 cal9 mol−1 K −1 ) ∆G
(a) 100
(b) 10
(c) 2 (d) 0901 13. The standard enthalpy of the decomposition decomposition of N 2OI to NO2 is 5D90I ! and ! and standard entropy of this this reac reacti tion on is 1F9 1F9F F ! !K 9 The standa standard rd free free o energy change for this reaction at 25 C is
14.
15.
(a) 5;E ! (b) (b) A 5;E 5;E ! (c) (c) A 59; 59;E E ! (d) (d) 59;E 59;E ! 3pontaneity of a chemical reaction is decided by the negative change in (a) !nternal energy (b) $nthalpy (c) $ntropy (d) #ree energy #or a react eactio ion n at 25o C enthalpy enthalpy change and entr entrop opy y chan change ges s are are − 119F × 10; ! mol−1 and − 105 !
(d) S∆GR = S∆H R
(b) $nthalpy
∆G =
vapour
.hat .hat is the the free free ener energy gy chan change ge
1at
(c) ∆G for the reaction is negative
(a) $ntropy
#or the change H 2O(l) → H 2O(g)=P = 1atm&
of ' at ater a t 100o C an and 1at pressure pressure is converted into steam at 100o C and
(a) ∆H for the reaction is /ero
t cons consta tant nt pres pressu sure re and and temp temper erat atur ure& e& the the direction to the result of any chemical reaction is 'here& there is less amount of
V 1
190mole
'hich h of the the foll follo' o'in ing g stat statem emen ents ts is NaCl & 'hic
8.
V 2
(d) Condensation of 'ater ;F; ;F ;K spontaneously spontaneously at
correct (b) ∆G for the reaction is /ero
(d)
P2
;F;K (c) .ater does does not boil spontane spontaneousl ously y at ;F;
The relation relation ∆G = ∆H − T ∆S 'as given by (a) 4olt/mann
V 1
;F;K (b) .ater boils boils spontane spontaneously ously at ;F;
& ∆S o = −I !K −1mol mol−1
(c)
nRT log
P1
V 2
(a) H 2 O(l) is in euilibrium 'ith H 2O(g)
= −I00 ! mol
= 200 ! mol mol
nRT log
nRT ln
This indicates indicates that
(b) ∆H
(c) ∆GT =
∆GT =
T = ;F;K & the the free free energ energy y chan change ge
The relation relation bet'een bet'een ∆G and ∆H is (a) ∆H = ∆G − T ∆S
nRT ln
∆GT = 10.
P2 (b) P1
(a) ∆GT =
16.
17.
mol mol−1K −1
resp respec ectiv tively ely9 .hat .hat is the the
Jibbs free energy (a) (a) 1590 15905 5 ! (b) (b) 1E95 1E95E E ! (c) (c) 2955 955 ! (d) (d) 2295 22955 5 ! 4ornLHaber cycle is used to determine (a) Crystal energy (b) $lectron anity (c) attice energy (d) ll of these Jibbs free energy G& enthalpy H and entropy S are interrelated as in (a) G = H + TS
(b) G = H − TS
Thermodynamics and Thermochemistry Thermochemistry 179 Thermodynamics
(d) G = S = H 18. The essential condition for the feasibility of a reaction is that (a) The reaction should be e"other e"othermic mic (b) The entro entropy py of produc products ts must must be larger larger than that of reactants (c) The react reaction ion is to be accom accompan panie ied d 'ith 'ith free free energy decrease (d) The react reaction ion has to posse possess ss high high activa activatio tion n energy 19. The correct correct relationship relationship bet'een bet'een free energy chan change ge in a reac reacti tion on and and the the corr corres espo pond ndin ing g K euilibrium constant c is (c) G − TS = H
20.
(a)
∆G =
(c)
∆G
o
RT ln K c
=
RT ln K c
24.
25.
− ∆G
o
=
(a) (dS)V & E
<
0&(dG)T & P
<
0
(b) (dS)V & E
>
0&(dG)T & P
<
0
(c) (dS)V & E
=
0&(dG)T & P
=
0
(d) (dS)V & E
=
0&(dG)T & P
>
0
26.
1 2
∆G = ∆H +
T 9C -
3tandard enthalpy and standard entropy changes for for the the o"ida "idati tion on of ammo ammoni nia a at 2ED K are −1
mol ;D2 ;D2 9HI! mol
(a) (a) A I;E I;E9; 9; ,@ ,@ mol−1
mol−1 (b) (b) A 52;9 52;92 2 ! mol
mol−1 (c) (c) A 221 22191 91 ! mol
mol−1 (d) (d) A ;;E9 ;;E9; ; ! mol
#or spontaneity of a cell& 'hich is correct
(a) (a) A E;; E;; cal (c) (c) A1E; E; cal 28. The
an nd ∆H a
(b) (b) A F;D F;D cal (d) (d) N E;; E;; cal ∆S
for for a react action ion at one atmo atmos spheric ric pressu ssure are N;0955 0955D D ! and −1 090HH 0HH! respectively respectively99 The temperature at 'hich 'hich the free free ener energy gy chang change e 'ill 'ill be /ero /ero and belo' of this temperature the nature of reaction 'ould be (a) ID; K & spontaneous (b) (b) II; K & nonLspontaneous (c) II; K & spontaneous (d) (d) I; K & nonLspontaneous
(d) E9E2× 10H Pa 22. The free energy energy change for the follo'ing reactions are given belo'&
H 2 (g) +
(d)
1000o C is
(c) E9E2× 10F Pa
O2(g) →
C(') + O 2 (g)→ CO 2 (g)
(c) ∆H = ∆G − T ∆S
T ∆S
27. The free energy energy for a reaction having ∆H = ;1I00ca= 9 ∆S = ;2 calK −1 mol−1 at
(b) E9E2× 10D Pa
2CO2(g) + H 2O(l)=∆G o
(b) ∆G = ∆H +
(c) ∆G = +e& ∆E = +e
transformed diamond at 2ED K is is
2
(a) ∆G = ∆H − T ∆S
(b) ∆G = −e& ∆E = 0
the pres pressu sure re at 'hic 'hich h grap graphi hite te 'ill 'ill be mol−1 & the
5
JibbPs free enrgy (G) is dened as
(d) ∆G = −e& ∆E = +e
2925 2925 and ;9;1 g cmA;& respectively9 !f the standard standard o free energy energy di+erence di+erence (∆G ) is eua euall to 1DE5 1DE5 !
C2H 2(g) +
(d) 1;E19
(a) ∆G = 0& ∆E = 0
21. The dens densitie ities s of graphi graphite te and and diamon diamond d at 2ED 2ED K are
(a) E9E2× 105 Pa
(c) A 1;D91D
−1 −1 9H !K mol & and − 1I5 respectively respectively99 3tandard Jibbs Jibbs energy energy change change for the same reaction at 2ED K is
RT ln K c
!n an irreversible process ta,ing place at constant T and and P and in 'hich only pressureLvolu pressureLvolume me 'or, is being being done& done& the chang change e in Jibbs Jibbs free free ener energy gy (dG) and change in entropy entropy (dS) & satisfy the criteria
(b) A 1;D19D
−
(b) −∆G = RT ln K c (d)
(a) 1 1; ;9D1
(e) (e) I; K & spontaneous = −12;I!
∆G
O 2(g)→ H 2O(l)
o
= −;EI!
∆G
o
= −2;F 2;F!
.hat is the standard free energy change for the g) ') g) + 2 C ( → C 2H 2( reaction H 2( (a) A 20 20E !
(b) (b) A 225 225E E !
(c) (c) N 225E 225E !
(d) (d) 20E !
23. The euilibrium euilibrium concentration concentration of the species in the
react eactio ion n * + ) ≡ C + ( are ;& 5& 10 and 15 ;00K the ∆G for mole&−1 respec respective tively ly at ;00 the reaction is
1.
2.
dsorption of gases on solid surface is generally e"othermic because (a) (a) $nth $nthal alpy py is posi positi tive ve
(b) (b) $ntr $ntrop opy y dec decre reas ases es
(c) (c) $ntr $ntrop opy y incr increa ease ses s
(d) (d) #ree ree ene energy rgy incr incre ease ase
T'o T'o mole of an ideal gas is e"panded isothermally isothermally and reversibl reversibly y from 1 litre litre ot 10 litre at ;00 ;00K 9 The enthalpy enthalpy change (in (a) (a) 119I !
! ) for the process is (b) (b) A119 A119I I !
Thermodynamics Thermodynamics and Thermochemistry 180
(c) 0 ! ! 3.
4.
(d (d) I9D !
(a) 1;9F cal cal
(b) 5F ! (b
(c) 59F × 10I !
(d) ll of the above above
(a) eversible eversible and !sothermal !sothermal (b) evers eversible ible and $"otherm $"othermic ic (c) 3pontane 3pontaneous ous and $ndot $ndother hermic mic (d) 3pontane 3pontaneous ous and $"other $"othermic mic
The value of heat generated 'hen ;95 gm HCl and I0 gm of gm of NaOH reacts during neutrali/ation (b) (b) 1;9F 1;9F cal
14.
(a) (∆H − T ∆S) must be negative
.hen a gas undergoes adiabatic e"pansion& it gets cooled due to
(b) (∆H
15. The total amount of energy energy in the universe is
"ed& but (a) 7isorder is increasing (b) ightning is increasing (c) atter is increasing (d (d) Jravitation is decreasing
The heat content content of a system system is called called (a) !nternal en energy
(b) $ntropy
(c) #ree energy
(d) $nthalpy
To To calculate the amount of 'or, done in Voules during reversible isothermal e"pansion of an ideal gas& the volume must be e"pressed in (a) m; on only
(b) dm; only
(c) cm; on only
(d) ny one of them
16.
!f for a given substance melting point is T ) and fre free/in /ing poin oint is
T 4 T 4
∆S
(a)
10.
(a) 1 B 1
(b) F B 2
(c) F B 5
(d) 5 B F
9 The value value of ∆E
(d) ∆S
17.
T
T 4
T T 4
∆S
!n endothe endothermic rmic reaction& reaction& the value valueT of change change in T
(a) (a) A09; A09;02 02I I !
(b) (b) 09;0 09;02I 2I !
enthalpy (∆H ) is
(c) 295 95F !
(d) (d) A090 A0900F 0F !
(a) -ositive
(b) *egative
(c) ero
(d) *o *one of these
$nthalpy of solution of NaOH (solid) in 'ater is − I1 mol−1 9 .hen NaOH is dissolved in 9H ! mol 'ater& the temperature of 'ater (a) !ncrease (b) 7ecreases
18.
(d) #luctuates
!n 'hich of the follo'ing entropy decreases : (a) Crystalli Crystalli/atio /ation n of sucrose sucrose from solution solution (b) usting usting of iro iron n
#or conve conversi rsion on C (graphi (graphite te)) ∆S is (a) ero (c) *egative
13.
T
(c)
.hich of the follo'ing 'ould be e"pected to have the largest antropy per mole (a)
SO2Cl 2(')
(b) SO2Cl 2(g)
(c)
SO2Cl 2(l)
(d) SO2(g)
19. The
enthalpies enthalpies of formation of
Cr 2O; ar are 2 *l + Cr 2O;
→
C (diamond) the
(b) -o -ositive (d) n,no'n
#or a reaction ∆H = E90D! mol−1 and
20.
−15EH !
∆H
respectively9
(c) elti elting ng of ice (d) 6apori/ati apori/ation on of camphor camphor 12.
T
T
The enthalpy change for the reaction of 50900 ml of ethy ethyle lene ne 'ith 'ith 5090 50900 0 ml of H 2 at 195 195 atm
(c) 7oes not change indenitely 11.
∆S
(b) T
(dW ) for diatomic gas is
∆H = −09;1!
T * & then then corre correct ct variat variation ion
sho'n sho'n by graph graph bet'e bet'een en entr entropy opy change change and temperature is
!n an isobaric process& the ratio of heat supplied to the system (dQ) and 'or, done by the system
pressur pressure e is 'ill be
T ∆S) must be negative
(c) ∆H must be negative
(d) $nergy $nergy used used in doing doing 'or, 'or,
9.
+
(d) ∆S must be negative
(c) 7ecrea 7ecrease se in in veloc velocity ity
8.
#or a reaction to occur spontaneously
(c) ore ore than than 1;9F 1;9F cal (d) (d) 10D 10D ,cal ,cal
(b) #all in temp temperat erature ure
7.
mol−1
.hich .hich of the follo'ing follo'ing stateme statements nts is correc correctt for the reaction
(a) oos oos of ,inet ,inetic ic energ energy y
6.
−1
Heat of neutrali/ation of strong acid against strong base is constant and is eual to
(a) F95 cal 5.
∆S = ;59F !K
→
*l2O;
an and
for
and
! −11;I
the
reaction
2Cr + *l2O; is
(a)
−2F;0 !
(b)
! −IH2
(c)
−1;H5 !
(d)
+
2F;0!
Heat of reaction at constant volume is measured in the apparatus (a) 4omb calorimeter (b) Calorimeter (c) -y,nometer (d) -yrometer
Thermodynamics and Thermochemistry Thermochemistry 181 Thermodynamics 21.
.hich of the follo'ing gas has the highest heat of combustion (a) ethane (b) $thane (c) $thylene (d) cetylene 22. The amount of heat measured measured for a reaction in a bomb calorimeter is
23.
25.
26.
27.
28.
29.
burnt burnt in a bomb calorimeter calorimeter at 25o C increases the temperature of 1D9EI g of 'ater by 09H;2 H;2o C 9!f the specic heat of 'ater at 25o C is 09EED cal calgLdeg& deg& the value of the heat combustion of ben/oic acid is
(a) ∆G
(b) ∆H
(a) (a) FF19 FF191 1 cal
(b) (b) DF19 DF192 2 cal
(c) ∆E
(d) P∆V
(c) (c) DD191 191 cal
(d) (d) ED19 ED191 1 cal
#or an endothermic reaction 'here ∆H represents the enthalpy of the reaction in !0mole& !0mole& the minimum minimum value value for the energy energy of activati activation on 'ill be (a) (a) ess ess than than ∆H
24.
31. The heat liberated 'hen 19DE g of ben/oic acid is
32.
(b) (b) er ero
(a) 2D !
(c) (c) ore ore than than ∆H (d) (d) $ua $uall to ∆H The heat of neutrali/ation of a strong acid by a strong base is nearly eual to (a) (a) N 5F9; 5F9;2 2 ! (b) (b) A 5F9; 5F9;2 2 ! (c) N 1; 1;9F ! 9F ! (d) (d) A 1;9F 1;9F ! 4ec,mann thermometer is used to measure (a) (a) High igh te tempe mperatu raturre (b) (b) o' te tempe mperat rature (c) (c) *orm *ormal al temp temper erat atur ure e (d) (d) ll ll temp temper erat atur ure e The heat reuired reuired to raise the temperature temperature of a body by 1 K is is called (a) 3pecic heat (b) Thermal capacity (c) .ater e euivalent (d) *one of th these echanical 'or, is specially important in system that contain (a) 3olidLliuid (b) iuidLliuid (c) 3olidLsolid (d) malgam (e) (e) Jase Jases s >The uantity of heat 'hich must be supplied to decompose a compound into its element is eual to the heat evolved during the formation of that compound from the elements9? This statement is ,no'n as (a) (a) Hess Hess%s %s la' la' (b) @oule% @oule%s s la' (c) eAch eAchateli atelier%s er%s principl principle e (d) avoiser avoiser and and aplace aplace la' la'
33. The
(d) E !
enthalpy of neutrali/ation neutrali/ation of
NaOH is
91;! − 12
−1
mol mol
34.
(b) (b) I591 I5910 0 !
(c) (c) I519E 19E !
(d) (d) I591 I591E E !
!n thermod thermodynam ynamics& ics& a proces process s is called called reversi reversible ble 'hen (a) 3urr 3urrou oundi nding ngs s and and syste system m chang change e into into each each
other (b) (b) Ther There e is no boun bounda dary ry bet' bet'ee een n syst system em and and surroundings (c) The surroun surroundings dings are are al'ays al'ays in euilibrium euilibrium 'ith the system (d) (d) The The syst system em chan change ges s into into the the surr surrou ound ndin ings gs spontaneously 35.
36.
37.
.hich .hich of the the follo' follo'ing ing unit unit repr repres esen ents ts large largest st amount of energy (a) Calor/e
(b) !o$le
(c) Erg
(d) Electron olt
.hich of the follo'ing 'ill have the highest bond energy (a) 5 2
(b) Cl 2
(c) )r 2
(d) I 2
C(graphite)+ O2(g) → CO 2(g) −1
mol ∆H = −EI 905calmol
(d) !nQuence of pressure pressure on volume of a gas
C (diamond)+ O 2 (g)→ CO 2 (g)=
#or #or 'hich 'hich one of the follo'ing follo'ing reactions reactions&& ∆H is not eual to ∆E
mol ∆H = −EI 950calmol
therefore
(a) H 2(g) + I 2(g) < 2HI(g)
→ C(diamond= (a) C (graphite)
+
(c) N 2(g)
+
−1
o
= (b) C (diamond)→ C (graphite)
;H 2(g) < 2NH;(g)
o
NaOH(aq) < NaCl(aq) (d) HCl (aq) +
−1
∆H 2EDK = −I50calmol
O2(g) < CO 2( g)
+
H 2O
by
9 The enthalpy of
(a) (a) I951 I951E E !
(c) $uilibr $uilibrium ium constant constant
(b) C(')
HCN
ionisation of HCN 'ill be
Hess la' deals 'ith (b) ate ate of react reaction ion
(b) 1E !
(c) 10 !
(a) Changes Changes in in heat heat of reacti reaction on
30.
#or #or a hypoth hypothet etic ic react reaction ion * → ) & the activation activation energies for for'ard and bac,'ard reactions are 1E ! !mole and E ! !mole respecti respectively vely9 The heat of reaction is
−1
∆H 2EDK = +I50calmol
(c) Jraphite Jraphite is the the stable stablerr allotrope allotrope
Thermodynamics Thermodynamics and Thermochemistry 182
38.
39.
(d) 7iamond 7iamond is harder harder than than graphite graphite $nthalpy $nthalpy of formation formation of t'o compounds compounds + + and 1 and 1 are A DI ! and ! and A 15 ! respectively9 ! respectively9 .hich of the follo'ing statements is correct (a) + is is more stable than 1 than 1 (b) + is is less stable than 1 than 1 (c) 4ot 4oth + and 1 and 1 are unstable (d) + and 1 and 1 are are endothermic compounds #or the process dry ice
47.
→ → CO 2 (g)
;IF& 15 and I;5 ! mol−1 & the value of enthalpy change for the reaction
(a) ∆H is positive 'hile ∆ ρ is negative (b) (b) 4oth 4oth ∆H and ∆ ρ are negative (c) 4ot 4oth ∆H
H 2C
and ∆ ρ are positive
(d) ∆H is negative 'hile ∆ ρ is positive 40.
#or melt meltin ing g of ; moles oles of 'ate ater at 0o C o ∆G is (a) ero (c) A e
the
2
2EDK 41. The euilibrium constant of a reaction at 2ED
is 5 × 10−; and at 1000K is 2× 10−5 9 .hat is the sign of ∆H for the reaction (b) ∆H is negative
42.
43.
(c) ∆H is is positive (d) .hich ich of the the foll follo' o'in ing g temperature (a (a) *a *aphthalene (b) (c) NaCl (d) Consider the reactions
*one of these has
lo' lo'est
fus fusion ion
7iamond 2n
C(') + 2H 2(g) → CH I (g)&∆H
= − + cal
C(g) + IH (g) → CH I (g)&∆H
= − + 1 cal
CH I(g) → CH ;(g) + H (g)&∆H
= + 1 cal
The bond energy of of C − H bond is
44.
(b) + 1 calmol mo l−1
(c) + I calmol−1
(d) + 1 I calmol−1
−1
;E1 ;E1! mole
N ≡ N& H − H EI5 EI5 & I;H
and and
(b) 102! (d) 105!
45. The relation bet'een bet'een ∆G and and ∆ G = −n5E =
46.
the
cell
2
Cl2
→
cal) ( ∆H 2ED = −220H0
HCl HCl
(ii) OH(g) → H (g) + O(g)=∆H = I2I! The average average bond energy energy (in !) !) for 'ater is (a) IE0 (b) I2I (c) E1I (d) E1I2 50. .hen .hen 50cm; of 092 N H 2SOI is mi"ed 'ith
50cm; of
is (c) E0!
1
(b) (b) A 250 250 ! (d) (d) A 125 125 !
(i) H 2O(g) → H (g) + OH (g)=∆H = IE0!
respectively& the enthalpy of the
−E;!
H2 +
at
means (a) The heat heat absorbed 'hen one one gram molecule molecule of HCl is formed from its elements at 25o C is 22900 cal (b) The heat heat given given out 'hen 'hen one gram gram molec molecule ule of HCl is formed from its elements at 2ED K is 22900 cal (c) The heat absorbed 'hen one atom of hydrogen reacts 'ith one atom of chlorine to form one molecule of HCl at 25o C and one atmospheric pressure is 22900 cal (d) The heat absorbe absorbed d 'hen one gram euivale euivalent nt of HCl is formed from its elements at 2ED K is 22900 cal (e) The intrins intrinsic ic heat heat of one molecu molecule le of HCl is 2290 22900 0 cal cal more than the intrinsic heats of one one atom atom of hydr hydrog ogen en and and one one atom atom of chlorine
follo'ing follo'ing reaction reaction N 2(g) + ;H 2(g) → 2NH ;(g) (a)
CH 2 (g) + H 2 (g) → H ;C − CH ; (g)
49. The H 2O(g) molecule dissociates as
mol−1 (a) 1 calmol
Jive Jiven n the the bond bond ener energi gies es bonds are N−H
=
2ED K 'ill 'ill be (a) N 250 ! (c) (c) N 125 ! 48. The euation euation
1
(b) N e (d) npr npred edict ictabl able e
(a) ∆H = 0
(a (a) . he hen ∆G is nega negati tive ve&& the the proc proces ess s is spontaneous (b) (b) .he .hen ∆G is /ero& the process is in a state of euilibrium (c) .hen ∆G is positi positive ve&& the the proce process ss is nonL nonL spontaneous (d) *one *one of of thes these e !f at 2ED K the the bond energies of C − H& C − C& C = C and H − H bonds are respectively I1I&
E
for a cell is reaction 'ill be
spontaneous if (a) G is is negative (b) G is positive (c) E is i s negative (d) E is positive .hich of the follo'ing is not a correct statement:
51.
KOH 1 N KOH
& the heat liberated liberated is (a) (a) 119I 119I ! (b) (b) 5F9; 5F9; ! (c) 5F; ! (d) (d) 5F; 5F; ! #ollo'i ollo'ing ng reac reactio tion n occur occurrin ring g in an autom automobi obile le
2CD H1D(g) + 25O2(g) → 1HCO2(g) + 1DH 2O(g)9 The sign of ∆H & ∆S and ∆G 'ould be (a) N& N& A& N (b) A& A& N& A (c) A& A& N& N (d) N& N& N& A 52. #or the reaction
H 2(g) +
1 2
O 2(g) → H 2O(l)&∆H −1
∆S = −091H;! mol
9D = −2D5
! mol−
K −1 9 .hat is the value
Thermodynamics and Thermochemistry Thermochemistry 183 Thermodynamics
of free energy change at 2Fo C for the reaction (a)
−
2D1 9I ! − 2D1
(c)
−
−1
mol 2;H 2;H 9E! mol
9.
ssertion B
for the react reaction ion99 N 2(g) + O2(g) <
(b)
2NO(g) 9
mol mol−1 1
;;I 9F! mol−
(d) + ;;I9F ! mol−1
easo eason n 10.
ead ead the assertion assertion and reason carefully carefully to mar, the correct option out of the options given belo' B
8c9 8c9 8d9 8e9 8e9
I3 4ot 4ot a'' a''ert/o rt/on n and and rea' rea'on on are are tr$ tr$e and te te rea'on /' te correct e+-lanat/on o3 te a''ert/on. I3 4ot 4ot a''er a''ert/o t/on n and and rea'o rea'on n are are tr$e tr$e 4$t 4$t rea rea'on 'on /' not te correct e+-lanat/on o3 te a''ert/on. I3 a'' a''er ert/ t/on on /' /' tr$e tr$e 4$t 4$t rea' rea'on on /' /' 3al' 3al'e. e. I3 te a''ert a''ert/on /on and rea'on rea'on 4ot 4ot are are 3al'e 3al'e.. I3 a'' a''er ert/ t/on on /' /' 3al' 3al'e e 4$t 4$t rea rea'o 'on n /' tr$e tr$e..
1.
ssertion B
849
The enthalpy of formation gase aseous ous o"yge ygen mole molec cules les and an d unde un der r pre pr e ssur ss ure e 2EDK 1at
eason eason
2. 3. 4.
ssertion ssert ion eason ssert ss ertion ion eason ssertion
eason ason 5.
B B B B B
B
ssert ss ertion ion B eason eason
6.
B
B
sse ssert rtio ion n B eason eason
B
7.
sse ssert rtio ion n B
8.
eason B sse ssert rtio ion n B
eason ason
B
of at of
11.
12.
13.
B
sse ssert rtio ion n B
eason eason
8a9
∆H and ∆E are almost the same
B
sse ssert rtio ion n B
er eroth oth la' can can als also o be term termed ed as la' of thermal euilibirum9 euilibirum9
eason eason
B
T'o obVects in thermal euilibrium 'ith 'ith the third third one& one& are are in ther thermal mal euilibrium 'ith each other9
ssert ss ertion ion B
There There is no react reaction ion ,no'n ,no'n for 'hich 'hich is positive& yet it is ∆G spontaneous9
eason eason
B
#or photochemical photochemical reactions reactions ∆G is negative9
sse ssert rtio ion n B
Heat Heat of neut neutra rali lisa sati tion on of perc perchl hlor oric ic acid& HClOI ' 'iith NaOH is
is /ero9
The entropy of formation of gaseous o"ygen o"ygen molecule molecules s under under the same condition is /ero9 .e feel feel cold cold on touchi touching ng the the ice9 ice9 !ce is a solid form of 'ater9 $ntr $ntropy opy of ice is less less than than 'ate 'aterr9 !ce have cage li,e structure9 The heat absored during the isothermal isothermal e"pansion of an ideal gas against vacuum is /ero9 The The volu volume me occu occupi pied ed by the the molecules of an ideal gas is /ero9 bsolu bs olute te value values s of of inte intern rnal al ener energy gy of substance can not be determined9 !t is impossible to determine determine e"act values of constituent energies of the substances9 ass ass and volu olume are are e"ten tensive ive properties9 ass volume is also an e"tensive e"tensive parameter9 ola olar entrop tropy y of vap vapori/ ori/a atio tion of 'ater is di+erent from ethanol9 .ater is more polar than ethanol9 The The inc increase ase in inte interrnal ener nergy (∆E) for the vapor vaporiat iation ion of one mole of 'ater at 1 atm and ;F;K ;F; K is is /ero9 #or all all isot isothe herrmal mal proc proce esse sses ∆E = 0 9
ll ll reac reacta tant nts s and and prod produc ucts ts are gases9 The The enth enthal alpi pies es of neut neutra rali lisa sati tion on of strong strong acids acids and strong bases are al'ays same9 *eutralisation *eutralisation is heat of formation of 'ater9
same as is that of
HCl 'ith
NaOH 9 B
4oth HCl and HClOI are strong acids9
ssertion B
Heat absorbed in a reaction at constant temperature and constant volume is −∆G 9
eason 14.
eason 15.
16.
17.
18.
19.
∆G
B
shoul should d be negativ negative e for the reaction to be spontaneous9 spontaneous9
sse ssert rtio ion n B
T& - and 6 are state tate var varia iab bles les or state functions9
eason
Their values depends on the state of the system and ho' it is reached9
B
sse ssert rtio ion n B
!nt !nternal ener nergy property9
eason eason
B
!nterna !nternall energy energy depend depends s upon the amount of the system9
sse ssert rtio ion n B
#or the the comb combus usti tion on react eactio ions ns&& the the value of ∆H is al'ays negative9
easo eason n
The The comb combus usti tion ons s reac reacti tion ons s al'ays endothermic9
B
is
an e"tensive sive
are are
ssert ss ertion ion B
#or #or an an isot isothe herma rmall rev rever ersib sible le proce process ss Q = −w i9e i9e9 'or, 'or, done done by the the system euals the heat absorbed by the system9
eason eason
B
$nthalpy change (∆H ) is /ero for isothermal process9
sse ssert rtio ion n B
$nth $nthal alpy py of of forma formati tion on of of grap graphi hite te is is /ero but of diamond is not /ero9
Thermodynamics Thermodynamics and Thermochemistry 184
eason eason 20.
21.
B
$nthalpy of formation of most stable allotrope is ta,en as /ero9
sse ssert rtio ion n B
!f a ref refri rige gera rato torP rPs s door door is ,ep ,eptt open open room gets cooled9
eason eason
B
aterial ,ept inside the refrigerator reamins cool9
ssertion B
$nthalpy and entropy of any eleme lemen ntary ary sub substan stanc ce in the standard state are ta,en as /ero9
eason ason
22.
B
t /ero /ero degr degre ee abso absolu lute te&& the the const onstit itu uent part article icles s become ome completely completely motionless9
sse ssert rtio ion n B
proce process ss is call called ed adia adiaba bati tic c if the the system does not e"change heat 'ith the surroundings9
easo eason n
!t does does not not invo involv lve e incr increa ease se or decr decre eae in temp tempe eratu raturre of the the system9
B
Basic concepts 1
b
2
d
3
b
4
c
5
c
6
d
7
d
8
c
9
c
10
c
11
d
12
d
13
a
14
c
15
b
16
b
17
d
18
a
19
b
20
b
21
d
22
b
23
c
24
c
25
d
26
c
27
c
28
c
First law of thermodynamics thermodynamics and Hess law l aw 1
d
2
b
3
a
4
b
5
c
6
a
7
c
8
a
9
b
10
d
11
b
12
c
13
c
14
c
15
b
16
b
17
c
18
b
19
c
20
a
21
c
22
c
23
a
24
a
25
b
26
a
27
a
28
a
29
bc
30
c
31
b
32
c
33
b
34
a
35
c
36
b
37
c
38
b
39
d
40
c
41
d
42
a
43
c
44
a
45
c
46
c
47
b
48
c
49
d
50
b
51
a
52
d
53
b
54
c
55
a
56
b
57
d
58
d
IInd & IIIrd Law of thermodynamics and Entropy 1
c
2
d
3
d
4
b
5
b
6
d
7
a
8
d
9
b
10
c
11
c
12
c
13
d
14
d
15
c
16
b
17
d
18
a
19
a
20
a
21
d
22
c
23
a
24
d
25
c
26
d
27
c
28
b
29
c
30
b
31
b
32
d
33
d
34
a
35
c
36
b
37
c
38
a
39
c
40
c
41
c
42
c
43
c
44
d
45
b
46
a
47
c
48
d
49
d
50
c
51
c
52
b
53
a
54
c
55
c
56
c
57
a
58
b
59
d
60
b
61
b
62
d
63
a
64
c
65
a
66
c
67
b
68
b
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