14-04-08-Svs Surface Chemistry Che -Assignment (1)

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Sri Chaitanya IIT- JEE Academy CHEMISTRY – ASSIGNMENT [SURFACE CHEMISTRY] Sr.IIT ************************************************************************************ 1.

Physical adsorption is appreciable at (A) Higher temperature (C) At room temperature

2.

(B) Lower temperature (D) 100C

The rate of chemisorption (A) Decreases with increase of pressure (C) is maximum at one atmospheric pressure

3.

Sorption is the term used when (A) adsorption takes place (C) both takes place

4.

Adsorption on solid is reversible Adsorption increase with increase in temperature Absorption is spontaneous Both enthalpy and entropy of adsorption are negative

The heats of adsorption in physisorption lie in the range (KJ/mol) (A) 40 – 400

6.

(C) 20 – 40

(D) 1 – 10

(B) Covalent

(C) Vander Waals

(D) H-bonding

How many Layers are adsorbed in chemical adsorption? (A) 1

8.

(B) 40 – 100

In physical adsorption, the forces associated are (A) Ionic

7.

(B) absorption takes place (D) desorption takes place

Which one of the following characteristics is not correct for physical adsorption? (A) (B) (C) (D)

5.

(B) is independent of pressure (D) increases with increase of pressure

(B) 2

(C) 3

(D) 4

Chromatography is a technique based on (A) Solubilities of solute (B) Adsorption of solute (C) Chemical adsorption followed by dispersion (D) Differential adsorption of different constituents of a mixture

9.

Which characteristic of adsorption is wrong? (A) Physical adsorption in general decreases with temperature (B) Physical adsorption in general increases with temperature (C) Physical adsorption is a reversible process (D) Adsorption is limited mainly to the surface only

10.

The volumes of gases H2, CH4, CO2 and NH3 adsorbed by 1 g of charcoal at 288K are in the order (A) H2 > CH4 > CO2 > NH3 (C) CO2 > NH3 > H2 > CH4

11.

(B) CH4 > CO2 > NH3 > H2 (D) NH3 > CO2 > CH4 > H2

The slope of the straight line graph between log x/m and log P for the adsorption of a gas on solid is (A) k

(B) log k

(C) n

(D) 1/n

2 12.

According to Langmuir adsorption isotherm, the amount of gas adsorbed at very high pressure (A) (B) (C) (D)

13.

Reaches a constant limiting value Goes on increasing with pressure Goes on decreasing with pressure increases first and decreases later with pressure

Graph between log(x/m) and log P is a straight line at an angle 45 with intercept on y-axis, 0.3010. Calculate amount of the gas absorbed in gram per gram of the adsorbent when pressure is 0.2 atm. (A) 0.4

14.

(B)

Formation of SO3 in the chamber process Formation of SO3 in the contact process Hydrolysis of an ester in presence of acid Decomposition of KClO3 in presence of MnO2

The decomposition of hydrogen peroxide can be slowed down by addition of a small amount of acetamide. The latter act as (B) Promoter

(B) Negative catalyst (C) Auto catalyst

(B) Fe acts as a catalyst and Mo as a promoter (D)Fe acts as promoter and Mo as auto-catalyst

(B) Negative catalyst (D) Induced catalyst

Platinised asbestos is used as a catalyst in the manufacture of H 2SO4. It is an example of (A) Homogeneous catalyst (C) Auto-catalyst

22.

(D) Enzyme catalyst

TEL minimizes the knocking effect when mixed with petrol. It acts as (A) Positive catalyst (C) Auto–catalyst

21.

(D) Poison

In the Haber process of synthesis of NH 3 (A) Mo acts as a catalyst and Fe as a promoter (C) Fe acts as inhibitor and Mo as a catalyst

20.

(C) Moderator

In the reaction: KMnO4 + H2SO4 + H2C2O4  products, Mn++ ions act as (A) Positive catalyst

19.

(D)

Catalyst only accelerates the rate of a chemical reaction A catalyst can retard the rate of a chemical reaction A catalyst can control the speed of a reaction A catalyst alters the speed of a reaction

(A) Inhibitor 18.

(C)

Which one of the following is not the example of homogeneous catalysis? (A) (B) (C) (D)

17.

(D) 0.2

Which of the following statement is more correct? (A) (B) (C) (D)

16.

(C) 0.8

Which plot is the adsorption isobar for chemisorption?

(A)

15.

(B) 0.6

(B) Heterogeneous catalyst (D) Induced catalyst

The catalyst used in the manufacture of hydrogen by Bosch’s process is (A) Fe2O3

(B) Cr2O3

(C) Fe2O3 + Cr2O3

(D) Cu

3 23.

In the Ostwald’s process for the manufacture of HNO 3, the catalyst used is (A) Fe

24.

(B) Pt

(B) Number of free valencies (D) Amount used

Which of the following types of metals make the most efficient catalysts? (A) Transition metals (C) Alkaline earth metals

26.

30.

increases the free energy change in the reaction Decrease the free energy change in the reaction Does not increases and decreases the free energy change in the reaction Can either decreases or increase the free energy change depending on what catalyst we use

A catalytic poison renders the catalyst ineffective because (A) (B) (C) (D)

29.

A catalyst can initiate a reaction it does not alter the position of equilibrium in a reversible reaction A catalyst remains unchanged in quality and composition at the end of reaction Catalysts are sometimes very specific in respect of a reaction

A catalyst (A) (B) (C) (D)

28.

it is preferentially adsorbed on the catalyst it adsorbs the molecules of the reactants it combines chemically with the catalyst it combines with one of the reactant

Butter is a colloid formed when (A) Fat is dispersed in fat (C) Water is dispersed in fat

(B) Fat is dispersed in water (D) Suspension of casein in water

Lyophobic colloids are (A) Reversible

31.

(B) Alkali metals (D) Radioactive metals

Which is false for catalyst? (A) (B) (C) (D)

27.

(D) Mo

Efficiency of the catalyst depends on its (A) Molecular weight (C) Physical state

25.

(C) V2O5

(B) Irreversible

Sulphur sol contains (A) Discrete sulphur atoms (C) Water dispersed in solid sulphur

(C) Water loving

(D) Solvent loving

(B) Discrete sulphur molecules (D) Large aggregates of sulphur molecules

32.

When freshly precipitated Fe(OH) 3 is boiled with water in the presence of few drops of dil. HCl, a hydrated ferric oxide sol is obtained. The method is termed as (A) Electro dispersion (B) Peptization (C) Ultra filtration (D) Dialysis

33.

Greater the valency, the higher is the coagulating power of ion. This rule was introduced by (A) Hardy-Schulze

34.

(B) Graham

(D) Faraday

All colloidal solution show (A) Very high osmotic pressure (C) Low osmotic pressure

35.

(C) Kossel and Lewis

An examples of micelle is

(B) High osmotic pressure (D) No osmotic pressure

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36. 37. 38.

(A) As2O3 solution (C) Na2CO3 solution

(B) Ruby glass (D) Sodium stearate concentrated solution

Which is not shown by sols? (A) Adsorption (B) Tyndall effect

(C) Paramagnetism

(D) Flocculation

Which of the following is an emulsifier? (A) Soap (B) Water

(C) Oil

(D) NaCl

Micelles are (A) adsorbent solutes

(B) associated colloids (C) adsorbed surfaces

(D) Ideal solution

39.

Substances whose solutions can readily diffuse through animal membranes are called (A) Colloids (B) Crystalloids (C) Electrolytes (D) Non-electrolytes

40.

The size of the colloidal particles is in between (A) 10–7 – 10-9 cm.

41.

Colloids are purified by (B) Precipitation

(C) Dialysis

(D) Filtration

(C) Dissolved

(D) Does not change

When excess of electrolyte is added to a colloid it? (A) Coagulates

44.

(D) 10–2 – 10–3 cm

Precipitating the colloidal particles Purifying the colloidal sol Dispersing the precipitate in to colloidal sol Movement of colloidal particles towards the opposite charged electrodes

(A) Brownian motion 43.

(C) 10–5 – 10–7 cm

Peptization is a process of (A) (B) (C) (D)

42.

(B) 10–9 – 10–11 cm.

(B) Gets diluted

Bleeding is stopped by application of ferric chloride. This is because (A) (B) (C) (D)

the blood starts flowing in opposite direction the ferric chloride seats the blood vessel the blood reacts and forms a solid which seals the blood vessel the blood is coagulated and thus, the blood vessel is sealed

45.

Gold number is a measure of (A) the amount of gold present in the colloidal solution (B) the amount of gold required to break the colloid (C) the amount of gold required to protect the colloid (D) the protective power of the lyophilic colloid

46.

On addition of one ml solution of 10% NaCl to 10 ml. gold sol in presence of 0.0025 g of starch, the coagulation is just prevented. The gold number of starch is (A) 25

47.

(D) 0.025

(B) Pb4+

(C) Sr2+

(D) Na+

Brownian motion shown by colloidal particle is its ……. property. (A) Optical

49.

(C) 0.25

Which of the following has minimum flocculation value? (A) Pb2+

48.

(B) 2.5

(B) Electrical

(C) Kinetic

(D) Chemical

A freshly prepared Fe(OH) 3 precipitate is peptized by adding FeCl 3 solution. The charge on the colloidal particle is due to preferential absorption of

5 (A) Cl– ions 50.

(B) Fe+++ ions

(C) OH– ions

(D) None

Hardy-schulze rule state that (A) Non-electrolytes have better coagulating action on colloids than electrolytes (B) Sols are coagulated by effective ions whose charge is opposite to that of sol and the ions of higher charge are much more effective than the ions of lower charge. (C) Charge of the ions has no effect on the coagulation of a sol (D) Sols are coagulated only by those ions whose charges is similar to that of the sol

51.

Which is correct statement in case of milk? (A) Milk is an emulsion of fat in water (C) Milk is stabilized by protein

52.

Which of the following is most effective in causing the coagulation of ferric hydroxide sol? (A) KCl

53.

(B) KNO3

The modern theory of catalysis is based on (B) Atomic or molecular weights (D) Number of free valencies

In the manufacture of H2SO4 by contact process, the presence of As2O3 acts as (A) Catalytic promoter

56.

(B) Catalytic poison

(B) Negative catalysis (D) Positive catalysis

Haber’s process of NH3 requires iron as catalyst Friedel-craft’s reaction requires anhydrous AlCl 3 Hydrogenation of oils requires iron as catalyst Oxidation of SO2 of SO3 requires V2O5

Regarding criteria of catalyst, which one of the following statements is not true? (A) (B) (C) (D)

59.

(D) Auto catalyst

Which statement is wrong? (A) (B) (C) (D)

58.

(C) Induced catalyst

In oxidation of oxalic acid by KMnO4, the colour of KMnO4 disappears slowly in the start of reaction but disappears very fast afterwards. This is an example of (A) Auto catalysis (C) Induced catalysis

57.

(D)K3Fe(CN)6

Adsorption produces heat which increases the rate of reaction In the process of adsorption, the kinetic energy of the molecules increases The concentration of reactants at the active centers becomes high due to adsorption The activation energy of the reaction becomes high due to adsorption

(A) Active masses (C) Size of the particle 55.

(C) K2SO4

According to adsorption theory of catalysis, the reaction rate increase, because (A) (B) (C) (D)

54.

(B) Milk in emulsion of protein in water (D) Milk is stabilised by fat

The catalyst is unchanged chemically during the reaction. A small quantity of catalyst is often sufficient to bring about a considerable amount of the In reversible reaction, the catalyst alters the equilibrium position the catalyst accelerates the rate of reaction

Which is not correct for heterogeneous catalysis? (A) The catalyst decrease the energy of activation (B) The surface of catalyst plays an important role (C) The catalyst actually forms a compound with reactants

reaction

6 (D) There is no change in the energy of activation 60.

Which of the following statements about a catalyst is/are true? (A) (B) (C) (D)

61.

A catalyst accelerates reaction by brining down the free energy of activation A catalyst does not take part in the reaction mechanism A catalyst makes the reaction more feasible by making the G more negative A catalyst makes the equilibrium constant of the reaction more favourable for the forward reaction

Fe3+ ions coagulate blood. This shows blood contains colloidal particles bearing (A) Negative charge (C) No charge

62.

The gold numbers of A, B, C and D are 0.04, 0.002, 10 and 25, respectively. The protective powers of A, B, C and D are in the order (A) A > B > C > D

63.

(B) Positive charge (D) Either positive or negative charge

(B) B > A > C > D

(B) Electrophoresis (D) Brownian movement

The potential difference between the fixed charged layer and the diffused layer having opposite charge is called (A) Colloidal potential (C) Electrostatic potential

65.

(C) Au

(D) Pt

100 ml of 0.1 M AgNO3 + 100 ml of 0.1 M KI 100 ml of 0.1 M AgNO3 + 50 ml of 0.2 M KI 100 ml of 0.1 M AgNO3 + 50 ml of 0.1 M KI 100 ml of 0.1 M AgNO3 + 100 ml of 0.15 M KI

higher colligative properties compared of common colloidal sols lower colligative properties same colligative properties low molar mass

Which of the following ion has minimum flocculation value? (A) Cl–

70.

(B) Cu

Micelles have (A) (B) (C) (D)

69.

(C) Brownian movement (D) Dialysis

On adding AgNO3 solution into KI solution, a negatively charged colloidal sol is obtained when they are in (A) (B) (C) (D)

68.

(B) Cataphoresis

Which metal sol cannot be prepared by Bredig’s are method? (A) K

67.

(B) Zeta potential (D) None of these

Colloidal particles carry charge. This can be shown by (A) Tyndall effect

66.

(D) C > A > B > D

The movement of dispersion medium in an electric field when the dispersed particles are prevented from moving is called (A) Cataphoresis (C) Electro–osmosis

64.

(C) D > C > B > A

(B) SO4–2

(C) PO43–

(D) [Fe(CN)6]4–

A liquid is found to scatter a beam of light but leaves no residue when passed through the filter paper. The liquid can be described as (A) A suspension

(B) Oil

(C) A colloidal sol

(D) True solution

7 71.

Gelatin is mostly used in making ice creams in order to (A) (B) (C) (D)

72.

Prevent making of colloid Stabilise the colloid and prevent crystallisation Stabilise the mixture Enrich the aroma

At critical micelle concentration (CMC) the surfactant molecules (A) Decomposes (C) Associates

73.

(B) Becomes completely soluble (D) Dissociates

According to Hardy-Schulze law the order of coagulation power of cations will be (A) Na+ > Ba+2 > Al+3 (C) Ba+2 > Al+3 > Na+

74.

(B) Al+3 > Ba+2 > Na+ (D) Al+3 > Na+ > Ba+2

Which one of the following method is commonly used for destruction of colloid? (A) Dialysis (C) Filtration by animal membrane

75.

Position of non polar and polar part in micelles (A) (B) (C) (D)

76.

77.

Polar at outer surface but non polar at inner surface Polar at inner surface but non polar at outer surface Distributed over all the surface Are present in the surface only

Milk is a colloidal (A) Liquid is dispersed in a liquid (C) Gas is dispersed in a liquid

(B) Mol per litre C) Gram per litre

(B) Gum

(C) Gelatin

(D) Starch

Tyndall effect in colloidal solution is due to (A) absorption of light (C) reflection of light

81.

D) Mol per millilitre

Which one of the following substances is not used for preparing lyophilic sols? (A) Metal sulphide

80.

(B) more than that of H2O (D) none of these

Flocculation value is expressed in terms of (A) Millimole per litre

79.

(B) Solid is dispersed in a liquid (D) Sugar is dispersed in a liquid

Surface tension of lyophilic sol is (A) lower than that of H2O (C) equal than that of H2O

78.

(B) Condensation (D) By adding electrolyte

(B) scattering of light (D) presence of electrically charged particles

Lyophilic sols are more stable than lyophobic sols because (A) The colloidal particles have positive charge (B) The colloidal particles have no charge (C) The colloidal particles are solvated (D) These are strong electrostatic repulsions between the negatively charged colloidal particles

MULTIPLE CHOICE QUESTIONS MAY HAVE ONE OR MORE THAN ONE CORRECT OPTION. 82.

Which one of the following is a correct statement? (A) Physical adsorption is reversible in nature

8 (B) Physical adsorption involves vander waals forces (C) Rate of physical adsorption increases with increase of pressure on the adsorbate (D) High activation energy is involved in physical adsorption 83.

Adsorption is accompanied by (A) Decrease in entropy of the system (C) Decrease in free energy of system

84.

In chemical reaction, the catalyst (A) Alters the amount of products (C) Decreases of H for forward reaction

85.

(B) Decrease in enthalpy of the system (D) No change in free energy of system

(B) Lowers the activation energy (D) Increases H of forward reaction

Which of the following is/are not a property of hydrophilic sols? (A) (B) (C) (D)

High concentration of dispersed of phase can be easily attained Coagulation is reversible Viscosity and surface tension are nearly as that of water The charge on the particles depends on the pH value of the medium; it may be positive, negative or even zero

86.

The capacity of an ion to coagulate a colloidal solution depends on (A) its shape (B) the amount of its charge (C) the sign of the charge (D) its mass

87.

During electro osmosis of Fe(OH)3 sol (A) Sol particles move towards anode (B) Sol particles move towards cathode (C) the dispersion medium moves towards anode (D) the sol particles do not move in either direction The question given below consist of two statements each printed as ‘Assertion’ (A) and ‘Reason’ (R). While answering these questions you are required to choose any one of the following four responses : (a) If both (A) and (R) are true and (R) is the correct explanation of (A). (b) If both (A) and (R) are true but (R) is not the correct explanation of (A) (c) If (A) is correct but (R) is incorrect. (d) If (A) and (R) are both incorrect. (e) (A) is wrong (R) is correct

88.

Assertion: Lyophilic colloids are called as reversible sols. Reason: Lyophilic sols are liquid loving. (A) A

89.

(B) B

(C) C

(D) D

Assertion: Addition of AgNO3(aq.) to KI (aq.) gives negative sol whereas addition of KI (aq) to AgNO 3 gives positive sol of AgI. Reason: The sol particles adsorb the common ions present in solution and acquire their charge. (A) A

90.

(B) B

(C) C

(D) D

Assertion: Sol particles show Tyndall effect. Reason: The scattering is directly proportional to size of sol particle. (A) A

(B) B

(C) C

(D) D

9 91.

Assertion : The presence of catalyst a increases the speed of the forward and backward reactions to the same extent. Reason : Activation energy for both the forward and backward reactions is lowered to the same extent. (A) a (B) b (C) c (D) d

92.

Assertion : A catalyst speeds up a reaction but doesn’t participate in its mechanism Reason : A catalyst provides an alternative path of lower activation energy of the reactants. (A) a (B) b (C) c (D)d

93.

Assertion : Catalysts are always transition metals. Reason : Transition metals have variable oxidation state. (A) a (B) b (C) c

94.

(D) d

Assertion : For adsorption G, S and H all have negative values. Reason : Adsorption is spontaneous process accompanied by decreases in randomness. (A) a (B) b (C) c (D) d

95.

Assertion : Physical adsorption of molecules on the surface requires activation energy. Reason : Because the bonds of adsorbed molecules are broken. (A) a (B) b (C) c

96.

Match the following Columns (A) (B) (C) (D)

97.

(D) d

Column – I Coagulation Peptization Tyndall effect Dialysis

(P) (Q) (R) (S)

Column – II Scattering of light Purification of colloidal solution Addition of electrolyte Precipitation of colloidal solution

Match the following Columns Column – I (Colloidal solution) (A) Colloidion (B) Fog (C) Butter (D) Milk

Column – II (Disperesed phase) (P) Water (Q) Cellulose (R) Fat (S) Water

Column – III (Dispersion medium) (U) Ethanol (V) Oil (W) Air (X) Water

98.

1 gm of charcoal adsorbs 100 ml 0.5 M CH3COOH to form a monolayer, and thereby the molarity of CH3COOH reduces to 0.49. Calculate the surface area of the charcoal adsorbed by each molecule of acetic acid. Surface area of charcoal = 3.01 × 102 m2/gm. (IIT 2003, 2 Marks)

99.

Rate of physiorption increases with (a) (c)

100.

(b) increase in temperature (d) decrease in surface area

Adsorption of gases on solid surface is generally exothermic because (a) (c)

101.

decrease in temperature decrease in pressure

(IIT 2003, 3 Marks)

enthalpy is positive entropy increases

Lyophilic sols are (a)

Irreversible sols

(IIT 2004, 3 Marks)

(b) entropy decreases (d) free energy increase (IIT 2005, 3 Marks) (b)They are prepared from inorganic compound

10 (c) 102.

Coagulated by adding electrolytes

(d) Self-stabilizing

20% of surface sites are occupied by N 2 molecules. The density of surface site is 6.023 × 10 14 cm–2 and total surface area is 1000 cm2. The catalyst is heated to 300 K while N 2 is completely desorbed into a pressure of 0.001 atm and volume of 2.46 cm3. Find the number of active sites occupied by each N2 molecule.