CHM1046 Quizzes

Tittle: Ti

Chap aptter 12 ne new w qu quiz iz

Star Starte ted: d: Submit Submitted ted:: Time spent:

Janu Januar ary y 16, 16, 2010 2010 2:20 2:20 PM Januar January y 16, 2010 2010 3:04 3:04 PM 00:44:52

Total score:

9.05/10 = 90.5%

Total score adjusted by 0.0

Maximum possible score: 10

1 Calculate the weight percent of a solution made by mixing 72.1 g of sucrose, C12H22O11, in 495.65 g of water. Submit your answer to 2 decimal places. Student Response Value Answer: 12.70 12.70   100% 100% 12.7 12.70 0 Units: % 0. 0 % %

Score:

Correct Answer

1/1

2 Calculate the weight percent of a solution made by mixing 5.00 g of urea, (NH2)2CO in 67.02 g of  water. Submit your answer to 2 decimal places. Student Response Value 6.94   100% 100% 6.94 6.94 Answer: 6.94 0. 0 % % Units: %

Score:

Correct Answer

1/1

3 Calculate the mole fraction of a solution made by mixing 32.9 g of sucrose, C12H22O11, in 136.86 g of  water. Submit your answer to 3 decimal places. Student Response Value Answer: 0.012 0.012   100% 100%

Score:

Correct Answer

0.01 0.012 2

1/1

4 Calculate the molality of a solution made by mixing 15.2 g of urea, (NH2)2CO in 393.95 g of water. Submit your answer to 3 decimal places. Student Response Value 0.642   95% 95% Answer: 0.642

Correct Answer -1 6.42 6.42EE-1 1 (6.4 (6.42 2 × 10 )

Units:

Student Response Value m 5 .0 % m

Score:

1/1

Correct Answer

5 Calculate the molality of a solution made by mixing 14.8 g of urea, (NH2)2CO in 459.18 g of water. Submit your answer to 3 decimal places.

Student Response Value

0.537 7 Answer: 0.53 Units:

m

Score:

1/1

 

95% 95% 5 .0 %

Correct Answer

0.53 0.537 7 m

6 You are given an aqueous 20.0 m solution of ammonia, NH3. What is the weight percent of the solution? Student Response Value 25.4%   100% 100% Answer: 25.4%

Score:

Correct Answer

25.4 25.4

2/2

7 You are given a 89.0% solution of sulfuric acid, H2SO4. What is the molality of this solution? The density of the H2SO4 solution is 1.610 g/mL. Student Response Value

82.5 Answer: 82. Units:

m

Score:

2/2

 

95% 95% 5 .0 %

Correct Answer

82.5 m

8 Calculate the molality of ions in a solution made by mixing 6.32 g of KBr, MW=119.00, in 60.44 mL of water at 37.0°C. The density of water at this temperature is 0.9933 g/cm-3 Submit your answer  to 2 decimal places. Student Response Value Answer: 0.88   0%

Correct Answer

1.77

Units:

Student Response Value m 5.0% m

Score:

0.05/1

Title:

Chapter 13 new quiz

Started: Submitted: Time spent:

April 16, 2010 6:42 PM April 16, 2010 7:03 PM 00:20:31

Total score:

8/10 = 80%

Correct Answer

Total score adjusted by 0.0

Maximum possible score: 10

1 A reaction with the activation energy Ea= 219.00 kJ/mol, has a rate constant k = 1.400 x 102 at 988.00 Kelvin. Determine the rate constant when the temperature is changed to 238.00 Kelvin. R = -1 8.314 J K  mol-1 Student Response Correct Answer -35 4.56E-35 (4.56 × 10 ) Answer: 4.56E-35  

General Rearrange the two-temperature Arrhenius equation as shown on p507 of MF 3rd Edition Feedback: and solve for k  2 Score:

2/2

2 Calculate the half life of a first order reaction having a rate constant of 5.16 x 10 -4. Enter your  answer to 3 sig figs. Student Response Correct Answer 3 Answer: 1.34E3   1.34E3 (1.34 × 10 )

Score:

1/1

3 The rate constant for the decomposition of dinitrogen pentoxide to form nitrogen dioxide and oxygen gas has the rate constant 1.7 x 10-3 s-1. This is a first order reaction. How long would it take for for the reaction to be 89.00% to complete? Enter your answer to 1 decimal place even if that is more sig figs that you are entitled to report. Student Response Correct Answer Answer: 1298.4   1,298.4

General Apply the first order integrated rate equation rearranged to solve for t, with the initial Feedback: concentration as [A]o and the final concentration as [A]t. Score:

1/1

4 The rate constant for the decomposition of dinitrogen pentoxide to form nitrogen dioxide and oxygen gas has the rate constant 1.7 x 10-3 s-1. This is a first order reaction. If the initial concentration of dinitrogen pentoxide was 1.318 mol/L, how many seconds will it take for the concentration to reach 0.461 mol/L? Student Response Answer: 617.9   618

Correct Answer

General Apply the first order integrated rate equation rearranged to solve for t, with the initial Feedback: concentration as [A]o and the final concentration as [A]t. Score:

1/1

5 In a certain decomposition reaction, dinitrogen pentoxide decomposes to form nitrogen dioxide gas and oxygen gas. It was found that at 189 seconds the concentration of oxygen gas was 0.296 mol/L and at 764.8 seconds the concentration of oxygen gas was 0.625 mol/L. What is the rate of  decomposition of dinitrogen tetroxide over the specified time period in this reaction? Student Response Correct Answer -3 -1.14E-3 (-1.14 × 10 ) Answer: 1.14E-3  

General The rate of a reaction is the rate of change of some species. In this case we are measuring Feedback: the change in concentration with time. To solve this, we divide the change in concentration by the time taken for the change to occur. The units are M/s. See page 475 of your textbook. Score:

0/1

6 In a certain decomposition reaction, dinitrogen pentoxide decomposes to form nitrogen dioxide gas and oxygen gas. It was found that at 399 seconds the concentration of oxygen gas was 0.420 mol/L and at 715.4 seconds the concentration of oxygen gas was 0.967 mol/L. What is the rate of  formation of nitrogen dioxide over the specified time period in this reaction? Student Response Correct Answer -3 Answer: 3.46E-3   6.92E-3 (6.92 × 10 )

General

The rate of a reaction is the rate of change of some species. In this case we are measuring

Feedback: the change in concentration with time. To solve this, we divide the change in concentration by the time taken for the change to occur. The units are M/s. See page 475 of your textbook. Score:

0/1

7 The second order rate constant for a reaction is 3.2100 x 102 M-1s-1. If the initial reagent concentration is 0.93100 mol/L, determine the time (in seconds) required for the reagent concentration to reach 0.34600 mol/L. Student Response Answer: 5.66E-3   0.01

Correct Answer

General Apply the second order integrated rate equation rearranged to solve for t . Feedback: Score:

1/1

8 -6 Determine the activation energy Ea in kJ/mol for a reaction who's rate constant k  1 = 4.400 x 10 at -2 471.00 Kelvin changes to k  2 = 7.500 x 10 when the temperature is changed to 625.00 Kelvin. R = -1 8.314 J Enter your answer in kJ.K  mol-1

Student Response Correct Answer 2 Answer: 1.55E2   1.55E2 (1.55 × 10 )

General Rearrange the two-temperature Arrhenius equation as shown on p507 of MF 3rd Edition Feedback: and solve for Ea. Score:

1/1

9 A reaction with the activation energy Ea= 92.00 kJ/mol, has a rate constant k = 8.500 x 10-4 at 379.00 Kelvin. Determine the temperature required to increase the rate constant 5 times . R = 8.314 J K  1 mol-1 Student Response Correct Answer 2 Answer: 4.01E2   4.01E2 (4.01 × 10 )

General Rearrange the two-temperature Arrhenius equation as shown on p507 of MF 3rd Edition Feedback: and solve for T2 Score:

1/1

Chapter 14 new quiz Started: Submitted: Time spent:

February 22, 2010 9:43 PM February 22, 2010 10:03 PM 00:20:32

Total score:

10/10 = 100%

Total score adjusted by 0.0

Maximum possible score: 10

1. The reaction

2 B(aq) + D(aq)

A(aq) + 2 F(aq)

is currently found, in some aqueous mixture at 2 2oC, to be at equilibrium. Placing the reaction vessel in ice water causes an increase in B and D concentration, thus: Student Response A. the reaction shown must be endothermic. B. the rate of the forward reaction must be less than the rate of the reverse reaction. C. the concentration of A must be equal to the concentration of D. D. the rate of the forward reaction must be exactly equal to the rate of the reverse reaction. E. The reaction must be exothermic.

Score:

Correct Answer

1/1

2. The reaction

2 B(aq) + D(aq)

A(aq) + 2 F(aq)

may be, in some aqueous mixture at 22oC, at equilibrium. If Q < K, you could definitely say that: Student Response A. the reaction shown must be endothermic. B. the rate of disappearance of B is exactly one-half the rate of gain of A. C. the rate of the forward reaction must be exactly equal to the rate of the reverse reaction. D. the rate of the forward reaction is not equal the rate of the reverse reaction.

Correct Answer

Student Response E. the concentration of A must be equal to the concentration of D.

Score:

Correct Answer

1/1

3. A mixture of 0.100 mol of CO2, 0.050 mol of H2, and 0.100 mol of H2O is placed in a 1.00 L vessel and reacts according to the reaction shown below. CO2 + H2 --> CO + H2O (all are gaseous) At equilibrium the container is found to contain 0.0916 M CO2. What is the equilibrium constant, K  c, for the reaction? Student Response Correct Answer Answer: 0.24   0.239

Score:

1/1

4. The chemical reaction

2 D(g) + F(g)

2 B(g)

for which K  Ho = 22.6 kJ/mol, is initially at equilibrium in a sealed 3.00 0 L p = 14.83 and adjustable volume vessel at 25oC. Altering conditions may cause the reaction to shift in order to reach a new equilibrium. What kind of adjustment is expected of the reaction if the following changes are made? (The answers are listed as effect of A; effect of B)

A. increased the volume of the vessel B. decreased the temperature of the system ? Student Response

Correct Answer

A. shift right; shift right B. shift left; shift left C. shift ldft; shift right D. shift right; shift left E. no shift; shift left Score:

1/1

5. Initially, .500 atm of H2 and .500 atm I 2 are mixed in an evacuated 1.0 L flask. The system is

allowed to come to equilibrium and it is found tocontain 0.320 atm HI. What is the equilibrium partial pressure of I2 for the reaction shown below? H2 + I2 --> 2 HI Student Response Correct Answer   0.340 Answer: 0.340

Score:

1/1

6. The reaction

A(s) + 2 B(g)

2 D(g)

exhibits K  c = 0.0277 at 342 K. If the standard enthalpy change for this reaction is 10.0 kJ/mol, what is the value of K  c for the following reaction ?

D(g) Student Response Answer: 6.01   6.01

Score:

B(g) + 1/2 A(s)

Correct Answer

1/1

7. A mixture of A(aq) and B(aq) associated with the reaction

A(aq)

2 B(aq)

for which the numerical value of K  c is 4.26, is initially prepared to contain [A] = 0.500 M and [B] = 1.81 M. As this system progresses toward equilibrium, we can con fidently predict Student Response A. the concentrations of both A and B will decrease. B. the concentration of A will increase, while the concentration of B will decrease. C. no change will occur in the concentration of either A or B. D. the concentrations of both A and B will increase. E. the concentration of A will decrease, while the concentration of B will increase.

Score:

1/1

Correct Answer

8. Given the chemical reaction

3 A(g) + 2 B(s)

2 D(g)

What is the equilibrium constant, K  p, expression for the reverse reaction? Student Response

Correct Answer

A. B. C. D. E. Score:

1/1

9. Under a set of unspecified conditions, the reaction

H2(g) + O2(g) + Cl2(g)

2 HOCl(g)

has K  p = 0.0698. What is the value of K  p for the reverse reaction ? Student Response Answer: 14.3   14.3

Score:

Correct Answer

1/1

1 K  p = 0.233 for the following reaction at 470° C. A (g) + B (s) = 2 C (g) What is the correct value of K  c? Enter your answer to 4 decimal places. e.g. 0.0025 Student Response Correct Answer   0.0038 Answer: 0.0038

Score:

1/1

Title:

Chapter 16 new quiz

Started: Submitted: Time spent:

April 16, 2010 7:04 PM April 16, 2010 7:26 PM 00:22:16

Total score:

8/10 = 80%

1.

Buffer Calculation 1

Total score adjusted by 0.0

Maximum possible score: 10

Calculate the pH of a buffer solution made by mixing 34 ml of a 0.11 M potassium acetate solution with 65 ml of a 0.10M acetic acid solution. Give the pH to two decimal places. Student Response Value Answer: 4.50   100%

Score:

2.

Correct Answer

4.50

1/1

Buffer Conceptual 2 Which of the following combonations will result in the creation of a buffer? Select all that apply. Student Value Response 50% A. mixing 0.50 mol NaOH with 1.0 mol HOBr  50% B. mixing 0.25 mol HCl with 1.0 mol CH3NH2 C. mixing 0.50 mol HCl with 1.0 mol HOBr  D. mixing 1.0 mol HCl with 0.50 mol NH3

Correct Answer

Feedback 

good!

Good!

Student Value Response E. mixing 0.50 mol NaOH with 0.50 mol HOBr 

Score:

3.

Correct Answer

Feedback 

1/1

Buffer Conceptual 1 Which of the following combonations will result in the creation of a buffer? Select all that apply. Student Value Response 50% A. mixing 0.50 mol HCl with 1.0 mol NH3 B. mixing 0.50 mol HCl with 0.50 mol NH3 C. mixing 1.0 mol HCl with 0.50 mol NH3 D. mixing 0.50 mol HCl with 1.0 mol NH4Cl 50% E. mixing 0.25 mol NaOH with 1.0 mol HF

Score:

4.

Correct Answer

Feedback 

good!

Good!

1/1

Buffer Mixture 2 Calculate the pH of a buffer solution made by mixing 31.1 g of potassium formate into

1 L of a 0.09 M solution of formic acid. Give the pH to two decimal places. Student Response Value Answer: 4.36   100%

Score:

5.

Correct Answer

4.35

1/1

Buffer of pH 4 Which of the following sets of conjugate pairs would you select to make a buffer with a pH of 3.35? Student Value Response A. nitrous acid and sodium nitrite B. lactic acid and sodium lactate C. hydrazine 0% and hydrazinium +1 D. benzoic acid and sodium benzoate E. arsenious acid and sodium arsenate

Score:

6.

Correct Answer

Feedback 

0/1

Buffer of pH 1 Which of the following sets of conjugate pairs would you select to make a buffer with a pH of 9.22? Select one answer. Student Value Response 0% A. arsenious acid and sodium arsenate B. benzoic acid and sodium benzoate

Correct Answer

Feedback 

Student Value Response C. ammonia and ammonium chloride D. nitrous acid and sodium nitrite E. hydrazine and hydrazinium +1

Score:

7.

Correct Answer

Feedback 

0/1

Equivalence point Calculate the volume of .025 M HCl required to titrate 50.0 mL of 0.046M NaOH solution to the equivalence point. State your answer to one decimal place in mL. Student Response Value     100% Answer: 92.0

Score:

8.

Correct Answer

92.0

1/1

SA/SB titration 2 Calculate the pH of a solution resulting from the titration of 50mL of 0.044M HBr with 25 mL of 0.102M KOH. Give your answer to two decimal places. Student Response Value Answer: 11.67   100%

Score:

9.

Correct Answer

11.67

1/1

WA SB Titration pKa pt What is the pH of a solution resulting from the titration of 50 mL of 0.050 M formic acid solution, HCOOH, with 25 mL of 0.050 M NaOH solution? Calculate your answer  to two decimal places. Student Value Response A. pH = 2.90 B. pH = 3.74 100% C. pH = 2.60 D. pH = 6.01

Correct Answer

Feedback 

easy, wasn't it!

Student Value Response

Correct Answer

Title:

Chapter 17 new quiz

Started: Submitted: Time spent:

April 3, 2010 12:59 PM April 3, 2010 1:06 PM 00:07:23

Total score:

8.02/10.02 = 80.0399%

Total score adjusted by 0.0

Feedback 

Maximum possible score: 10.02

1. Question 107 Under which of the following conditions would one mole of Ne have the highest entropy, S? Student Response

Value

Correct Answer

Feedback  

A. 27 C and 25 L B. 137 C and 25 L C. 27 C and 35 L 100%

D. 137 C and 35 L Score:

1/1

2. Question 103 The following pictures represent three equilibrium mixtures for the interconversion of A, B, and C molecules (unshaded spheres) into X, Y, and Z molecules (shaded spheres), respectively. What is the sign of

G

Student Response

A. G (1) =

for each of the three reactions?

Value

Correct Answer

Feedback  

Student Response

-;

Value

G (2) =

+;

G (3) =

0 100%

B. G (1) = -;

G (2) =

0;

G (3) =

+ C. G (1) = 0;

G (2) =

-;

G (3) =

+ D. G (1) = +;

G (2) =

0;

G (3) =

-

Correct Answer

Feedback  

Score:

1/1

3. Question 096 Consider the reaction 2A(g  ) A2(g  ). The following pictures represent two possible initial states and the equilibrium state of the system.

S, and What are the signs (+ or -) of  H, from initial state 2 to the equilibrium state?

Student Response

Value

Correct Answer

G

when the system goes

Feedback  

A. H  = +,

S  =

+, =+

G 0%

B. H  = +,

S  =

+, =-

G

C. H  = -, S  = -, G=+ D. H  = -, S  = -, G=Score:

0/1

4. Question 085 In figure (1) below oxygen molecules, represented by un shaded spheres, and chlorine molecules, represented by shaded spheres, are in separatecompartments. Figure (2) shows the equilibrium state of the system after the stopcock separating the two co mpartments is opened. Assuming the oxygen

and the chlorine behave as ideal gases, what are the signs (+, -, or 0) of  for this process?

Student Response

Value

Correct Answer

H  ,

Feedback  

A. H  = +,

S  =

-, +

G= 100%

B. H  = 0,

S  =

+, =-

G

C. H  = 0,

S  =

-, +

G=

D. H  = -, S  = +, G=Score:

1/1

5. Question 081 If 

G is small and positive,

Student Value Response A. the forward reaction is spontaneous

Correct Answer

Feedback  

S  , and

G

Student Value Response and the system is far  from equilibrium. B. the forward reaction is spontaneous and the system is near  equilibrium. C. the reverse reaction is spontaneous and the system is far  from equilibrium. D. the reverse 100% reaction is spontaneous and the system is near  equilibrium.

Score:

Correct Answer

Feedback  

Correct Answer

Feedback  

1/1

6. Question 071 If  Q increases Student Response

Value

A. G increases and the reaction becomes more spontaneous. 100%

B. G increases and the reaction

Student Value Response becomes less spontaneous.

Correct Answer

Feedback  

C. G decreases and the reaction becomes more spontaneous. D. G decreases and the reaction becomes less spontaneous. Score:

0.34/0.34

7. Question 069 G=

G

for a reaction

Student Value Response A. if  Q = K  . Q = 1. 100% B. if  C. at STP. D. at the start of the reaction.

Score:

Correct Answer

Feedback  

Correct Answer

Feedback  

0.34/0.34

8. Question 040 During perspiration, Student Value Response A. the entropy of  the water  evaporated

Student Value Response decreases and the entropy of  the body decreases. B. the entropy of  the water  evaporated decreases and the entropy of  the body increases. 100% C. the entropy of  the water  evaporated increases and the entropy of  the body decreases. D. the entropy of  the water  evaporated increases and the entropy of  the body increases.

Score:

Correct Answer

Feedback  

0.34/0.34

9. Question 026 Under which of the following conditions would one mole of Ne have the highest entropy, S? Student Response

A. 27 C and 25 L B. 137 C and 25 L

Value

Correct Answer

Feedback  

Student Response

Value

Correct Answer

Feedback  

C. 27 C and 35 L 100%

D. 137 C and 35 L Score:

1

0.5/0.5

Question 030 Which should have the highest standard molar entropy at 25 Student Value Response A. Al(s) B. Al(l  ) ) 100% C. Al(g 

Correct Answer

C?

Feedback  

D. All three should have a standard molar  entropy of  zero. Score:

1

0.5/0.5

Question 041 A hot penny is dropped into cold water inside a polystyrene foam cup. Assuming negligible heat loss to the atmosphere and the cup, Student Value Response 0% A. the decrease in entropy of the penny is equal to the increase in

Correct Answer

Feedback  

Student Value Response entropy of  the water.

|

S  penny

|=| S  | water  B. the decrease in entropy of the penny is less than the increase in entropy of  the water. |

S  penny

|| S  | water  D. the entropy of  both the penny and the water  increases. Score:

0/1

1 Question 105

Correct Answer

Feedback  

What is the entropy change associated with the expansion of one mole of an ideal gas from an initial volume of  V  to a final volume of 6.50V  at constant temperature? Student Response

Value

Correct Answer

Feedback  

A. S  = -6.50 R ln (V  f/  V  i) 100%

B. S  =R ln 6.50 C. S  = 6.50 R ln (V  f/  V  i) D. S  = -R ln 6.50 Score:

1

1/1

Question 099 Consider the following gas-phase reaction of A2 (shaded spheres) and B2 (unshaded spheres):

Which of the above reaction mixtures is Student Value Response A. (1) B. (2) 100% C. (3)

Correct Answer

D. (4) Score:

Title:

1/1

Chapter 15 new quiz

G

of reaction =

G

Feedback  

?

Started: Submitted: Time spent:

March 7, 2010 2:39 PM March 7, 2010 3:01 PM 00:21:29

Total score:

8.5/10 = 85%

Total score adjusted by 0.0

Maximum possible score: 10

1 Consider the following generic weak acid reaction. HA + H2O H3O+ + A If a 0.0031M solution of HA has a pH of 3.08, calculate Ka for the acid HA. Enter your answer with two sig figs in the form: 2.3E-6 for 2.3 x 10 -4 Student Response Value Answer: 3.1E-4   100%

Score:

Correct Answer -4 3.1E-4 (3.1 × 10 )

1.5/1.5

2 -9 K  a = 2.0 x 10 for HOBr. Calculate the pH of a 0.1171M HOBr solution. Round the pH to two decimal places.

Student Response Value   100% Answer: 4.82

Score:

Correct Answer

4.82

1.5/1.5

3 Calculate the pH of a 2.38 x 10-4 M hydrazine solution. Show your answer to two decimal places and -7 use K  b = 8.9 x 10 . Student Response Value   100% Answer: 9.16

Score:

Correct Answer

9.16

1.5/1.5

4 -8 Hypochlorous acid, HOCl, is a weak acid with a K  a of 3.50x10 . What is the pH of a 0.38M solution of KOCl? Use two decimal places in your answer.

Student Response Value Answer: 3.94   0%

Score:

Correct Answer

10.52

0/1.5

5 Refer to Appendix C, Tables C.1 and C.3 to decide which of the following salt solutions will produce a basic solution? You may select more than one answer. Student Value Response A. C5H5NHBr  B. KI 50% C. LiOBr D. NaCH3CO2 50%

Correct Answer

Feedback  

E. NH4Cl Score:

2/2

6 Refer to Appendix C, Tables C.1 and C.3 to decide which of the following salt solutions will produce a acidic solution? You may select more than one answer. Student Value Response A. LiOBr  B. NaCH3CO2 50% C. NH4Cl

D. C5H5NHBr 50% E. KI Score:

2/2

Correct Answer

Feedback