University of South Florida CHM 2046 16

University of South Florida

CHM 2046

16.2 Algorithmic Questions

1)The entropy change associated with the expansion of one mole of an ideal gas from an initial volume of Vi to a final volume of Vf at constant temperature is given by the equation, ΔS = R ln (Vf/Vi). What is the entropy change associated with the expansion of three moles of an ideal gas from an initial volume of Vi to a final volume of Vf at constant temperature?

1. 1. ΔS = R ln (Vf/Vi)
   2. ΔS =  3 mol × R ln (Vf/Vi)
   3. ΔS = R ln (Vf × 23/Vi)
   4. ΔS = R ln (Vf × 3!/Vi)

2. 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  4.50 V at constant temperature?
   1. ΔS =  4.50 R ln (Vf/Vi)
   2. ΔS = -4.50 R ln (Vf/Vi)
   3. ΔS = R ln 4.50
   4. ΔS = -R ln 4.50

3. Predict the sign of ΔS for each of the following systems, which occur at constant temperature

1. The volume of 2.0 moles of O2(g) increases from 44 L to 52 L.
2. The pressure of 2.0 moles of O2(g) increases from 1.0 atm to 1.2 atm.

1. I: ΔS = negative; II: ΔS = negative
2. I: ΔS = negative; II: ΔS = positive
3. I: ΔS = positive; II: ΔS = negative
4. I: ΔS = positive; II: ΔS = positive

4. Under which of the following conditions would one mole of He have the highest entropy, S?
   1. 17°C and  15 L
   2. 127°C and 15 L
   3. 17°C and 25 L
   4. 127°C and 25 L

Topic: Section 16.4 Entropy and Temperature Algo. Option: algorithmic

5. Which one of the following would be expected to have the lowest standard molar entropy, S°, at 25°C?

A) C10H22(s)

B) C10H22(l)

C) C14H30(s)

D) C14           OH(l)

1. 2. Short Answer Questions

1. Chemical and physical changes can be classified as spontaneous or nonspontaneous. At 25°C and 1 atm pressure the decomposition of water into hydrogen and oxygen is classified as

                     , and the melting of ice is classified as                             .

2. The sign (+ or –) of ?H is                              and the sign (+ or –) of ?S is                             for the evaporation of water.

3. A 1.0 mole sample of gas at STP has a                                entropy than 1.0 mole of gas at 273 K and 835 mm Hg.

4. The entropy of water at 25° is                            than the entropy of water at 35°C.

5. Standard molar entropies, S°, in J/K?mol, are given below each reactant and product in the reaction shown below. The standard entropy of reaction, ?S°, for this reaction is                                                  J.

CH4(g) + 2 O2(g) → CO2(g) + 2 H2O(l) 186.2                  205.0         213.6            69.9

6. A reaction for which ?H° = + 98.8 kJ and ?S° = + 141.5 J/K is                                        (spontaneous or nonspontaneous) at low temperatures and                         (spontaneous or nonspontaneous) at high temperatures.

7. A reaction has ?G° = + 21.5 kJ/mol, ?H° = + 25.0 kJ/mol, and ?S° = + 15.0 J/mol?K can become spontaneous at a temperature of                                          K.

8. Acetylene, C2H2, has a standard enthalpy of formation, ?H° = 226.7 kJ/mol, and a standard entropy change for its formation from its elements, ?S° = 58.8 J/K?mol. The standard free energy of formation of acetylene is                                                                           kJ/mol.

9. Standard free energies of formation, ?G°, in kJ/mol, are given below each reactant and product in the reaction shown below. The standard free energy of reaction, ?G°, for this reaction is                       kJ.

CH4(g) + 2 O2(g) → CO2(g) + 2 H2O(l)

– 50.8           0           – 394.4       – 237.2

Answer: – 818.0

10. The standard free energy for a reaction is ?G° = – 33.0 kJ. At 25°C the equilibrium constant for this reaction , Kp =                                          .

11. Cation C and anion A form an ionic compound for which Ksp = s², where s is the molar solubility of the ionic compound. Which of Figures I–III represent(s) possible results of the mixing of an aqueous solution containing cation C with an aqueous solution containing anion A?

• • only I
  • only III
  • both I and III
  • both I and II
  • only II

12. Cation C and anion A form an ionic compound for which Ksp = 4s³, where s is the molar solubility of the ionic compound. Which of Figures I–III represent(s) possible results of the mixing of an aqueous solution containing cation C with an aqueous solution containing anion A?

• • only III
  • only II
  • both I and II
  • only I
  • both I and III

13. Which of the following particulate views is/are consistent with a heterogeneous equilibrium?

I                                 II                                III

• • I only
  • II only
  • III only
  • II and III
  • I, II, and III

14. What is the solubility product expression for Al(OH)3?
    • Ksp = [Al³⁺][3OH^–]

B)     Ksp = 3[Al³⁺][OH^–]³

C) Ksp = [Al³⁺][OH^–]³

D) Ksp = [Al³⁺][3OH^–]³

E)     Ksp = [Al³⁺][OH^–]

3. Ksp = [Th][IO3]⁴
4.  

D) Ksp = [Hg2][I2]

E)     Ksp = [Hg⁺]²[I^–]²

19. What is the solubility product expression for Pb3(PO4)4? A) Ksp = [Pb³⁺]⁴[PO44–]³

20. What is the solubility product expression for Sn(IO3)2?
    •  

21. Figures I–IV represent ionic compounds formed upon the mixing of an aqueous solution containing cation C with an aqueous solution containing anion A. Identify the figure(s) that represent(s) products for which Ksp = s², where s is the molar solubility of the ionic compound.

• • only I
  • only II
  • only IV
  • only III
  • both I and II

22. Figures I–IV represent ionic compounds formed upon the mixing of an aqueous solution containing cation C with an aqueous solution containing anion A. Identify the figure(s) that represent(s) products for which Ksp = 4s³, where s is the molar solubility of the ionic compound.

• • both I and II
  • only II
  • only IV
  • only I
  • only III

23. Figures I–IV represent ionic compounds formed upon the mixing of an aqueous solution containing cation C with an aqueous solution containing anion A. Identify the figure(s) that represent(s) products for which Ksp = 108s⁵, where s is the molar solubility of the ionic compound.

• • only II
  • both I and II
  • only IV
  • only III
  • only I

24. What is the relationship between molar solubility (s) and Ksp for calcium fluoride? A)

B)

C)

D)

E)

25. What is the correct mathematical expression for finding the molar solubility (s) of Sn(OH)2?
    • 2s³ = Ksp
    • 4s³ = Ksp
    • 108s⁵ = Ksp
    • 2s² = Ksp
    • 8s³ = Ksp

26. The concentration of calcium carbonate in a saturated aqueous solution of the salt at 25°C is 6.71 ×10- 5 M. What is the Ksp of this sparingly soluble salt?

A)  4.50 ×10- 9

B)     1.21 ×10- 12

C)     5.47 ×10- 16

D)   8.19 ×10- 3

E)     4.06 ×10- 2

A)   9.30 ×10- 10

B)     1.13 ×10- 13

C)     2.34 ×10- 17

D)   5.52 ×10- 3

E)     3.12 ×10- 2

28. After mixing an excess PbCl2 with a fixed amount of water, it is found that the equilibrium concentration of Pb²⁺ is

1.6 ´ 10^–2 M. What is Ksp for PbCl2? A) 4.0 ´ 10^–6

B)     1.6 ´ 10^–5

C)     2.5 ´ 10^–4

D)   4.8 ´ 10^–2

E)     1.0 ´ 10^–6

29. The solubility of lead(II) sulfate is 4.0 ´ 10^–2 g/L. What is the solubility product constant for lead(II) sulfate? A) 1.7 ´ 10^–8

B)     1.3 ´ 10^–4

C)     1.6 ´ 10^–3

D)   4.6 ´ 10^–15

E)     8.9 ´ 10^–12

30. The solubility of silver(I) carbonate is 3.6 ´ 10^–2 g/L. What is the solubility product constant for silver(I) carbonate? A) 4.4 ´ 10^–15

B)     8.9 ×10- 12

C)     1.7 ´ 10^–8

D)   1.3 ´ 10^–4

E)     1.3 ´ 10^–3

A)  7.80 ×10- 16

B)     6.24 ×10- 15

C)     1.56 ×10- 15

D)   3.41 ×10- 3

E)     2.26 ×10- 2

32. The silver-ion concentration in a saturated solution of silver(I) chromate is 1.3 ´ 10^–4 M. What is Ksp for silver(I) chromate?

A) 2.9 ´ 10^–16

B)     4.2 ´ 10^–9

C)     8.8 ´ 10^–12

D)  1.1 ×10- 12

E)     1.7 ´ 10^–8

33. Which of the following salts has the highest molar solubility in water?

A)   SrCO3 (Ksp = 9.3 ´ 10^–10)

B)     BaSO4 (Ksp = 1.1 ´ 10^–10 )

C)     PbS (Ksp = 2.5 ´ 10^–27)

D) BaCrO4 (Ksp = 1.2 ´ 10^–10)

E)     AgCl (Ksp = 1.8 ´ 10^–10 )

34. Which of the following salts has the lowest molar solubility? A) SrCO3 (Ksp = 9.3 ´ 10^–10)

B)     MnS (Ksp = 2.5 ´ 10^–10)

C)     BaF2 (Ksp = 1.0 ´ 10^–6)

D) BaSO4 (Ksp = 1.1 ´ 10^–10)

E)     AgCl (Ksp = 1.8 ´ 10^–10)

35. Rank the following salts in order of increasing molar solubility. Salt Ksp

BaSO4       1.1 ´ 10^–10

AgCl           1.8 ´ 10^–10

BaCO3       9.1 ´ 10^–9

CdS            8 ´ 10^–27

PbSO4       1.8 ´ 10^–8

• • CdS < AgCl < BaSO4 < BaCO3 < PbSO4
  • CdS < AgCl < BaCO3 < BaSO4 < PbSO4
  • CdS < BaSO4 < AgCl < BaCO3 < PbSO4
  • PbSO4 < BaCO3 < AgCl < BaSO4 < CdS
  • PbSO4 < BaCO3 < BaSO4 < AgCl < CdS

36. A saturated solution of which of the following salts will have the lowest molar concentration of chromate ion? A) BaCrO4 (Ksp = 2.1 ´ 10^-10)

B)     CuCrO4 (Ksp = 3.6 ´ 10^-6)

C)     Ag2CrO4 (Ksp = 1.2 ´ 10^-12)

D) Hg2CrO4 (Ksp = 2.0 ´ 10^-9)

E)     Tl2CrO4 (Ksp = 9.8 ´ 10^-13)

37. A saturated solution of which of the following salts will have the greatest molar concentration of silver ion? A) Ag2S (Ksp = 8 ´ 10^-51)

B)     AgCl (Ksp = 1.8 ´ 10^-10)

C)     Ag2CrO4 (Ksp = 1.2 ´ 10^-12)

D) Ag2CO3 (Ksp = 8.1 ´ 10^-12)

E)     Ag4Fe(CN)6 (Ksp = 8.5 ´ 10^-45)

38. What is the solubility (in g/L) of aluminum hydroxide at 25°C? The solubility product constant for aluminum hydroxide is 4.6 ´ 10^–33 at 25°C.

A)   3.6 ´ 10^–31 g/L

B)     8.2 ´ 10^–10 g/L

C)     2.8 ´ 10^–7 g/L

D)   5.3 ´ 10^–15 g/L

E)     1.8 ´ 10^–31 g/L

39. What is the solubility (in g/L) of silver(I) bromide at 25°C? The solubility product constant for silver(I) bromide is 5.0 ´ 10^–13 at 25°C.

A) 9.4 ´ 10^–3 g/L

B)     9.4 ´ 10^–11 g/L

C)     1.3 ´ 10^–4 g/L

D) 4.7 ´ 10^–11 g/L

E)     7.9 ´ 10^–2 g/L

40. Rank the following metal sulfides in order of increasing molar solubility in water. Salt     Ksp

CoS                    4 ´ 10^–21

CuS                    6 ´ 10^–36

FeS                    6 ´ 10^–18

HgS                1.6 ´ 10^–52

MnS               2.5 ´ 10^–10

• • MnS < FeS < CoS < CuS < HgS
  • FeS < HgS < CoS < CuS < MnS
  • HgS < CuS < CoS < FeS < MnS
  • CuS < CoS < FeS < MnS < HgS
  • CoS < CuS < FeS < HgS < MnS

41. What is the molar solubility of silver(I) bromide at 25°C? The solubility product constant for silver(I) bromide is 5.0 ´ 10^–13 at 25°C.

A) 7.1 ´ 10^–7 M

B)     2.5 ´ 10^–13 M

C)     4.2 ´ 10^–4 M

D)   5.0 ´ 10^–5 M

E)     5.0 ´ 10^–13 M

42. What is the molar solubility of calcium sulfate at 25°C? The solubility product constant for calcium sulfate is 2.4 ´ 10^–5 at 25°C.

A)   2.4 ´ 10^–5 M

B)     3.5 ´ 10^–2 M

C)     1.2 ´ 10^–5 M

D)   1.8 ´ 10^–2 M

E)     4.9 ´ 10^–3 M

43. What is the molar solubility of barium fluoride at 25°C? The solubility product constant for barium fluoride is 1.0 ´ 10^–6 at 25°C.

A)   6.3 ´ 10^–3 M

B)     1.0 ´ 10^–6 M

C)     5.0 ´ 10^–7 M

D)   1.0 ´ 10^–3 M

E)     1.6 ´ 10^–2 M

44. What is the molar solubility of aluminum hydroxide at 25°C? The solubility product constant for aluminum hydroxide is 4.6 ´ 10^–33 at 25°C.

A)   2.3 ´ 10^–33 M

B)     6.8 ´ 10^–17 M

C)     4.6 ´ 10^–33 M

D) 3.6 ´ 10^–9 M

E)     1.0 ´ 10^–11 M

45. What is the solubility (in g/L) of barium chromate at 25°C? The solubility product constant for barium chromate is 1.2 ´ 10^–10 at 25°C.

A) 0.42 g/L

B)     3.0 ´ 10^–8 g/L

C)     1.5 ´ 10^–8 g/L

D) 0.079 g/L

E)     0.0028 g/L

46. What is the solubility (in g/L) of calcium fluoride at 25°C? The solubility product constant for calcium fluoride is 3.4 ´ 10^–11 at 25°C.

A) 0.00046 g/L

B)     2.7 ´ 10^–9 g/L

C)     0.016 g/L

D) 1.3 ´ 10^–9 g/L

E)     0.094 g/L

47. Pure water is saturated with slightly soluble calcium fluoride, CaF2. Which of the following is true concerning the equilibrium concentration of Ca²⁺?

A)

B)     [Ca²⁺] = [F^–] C)

D)

E)     [Ca²⁺] = Ksp

48. Which of the following salts has the lowest molar solubility in water? A) Ni(OH)2 (Ksp = 2.0 ´ 10^–15)

B)     Fe(OH)2 (Ksp = 8 ´ 10^–16)

C)     PbI2 (Ksp = 6.5 ´ 10^–9)

D) SrCO3 (Ksp = 9.3 ´ 10^–10)

E)     AgBr (Ksp = 5.0 ´ 10^–13)

49. Which of the following salts has the highest molar solubility in water? A) CaCO3 (Ksp = 3.8 ´ 10^–9)

B)     Ni(OH)2 (Ksp = 2.0 ´ 10^–15)

C)     Fe(OH)2 (Ksp = 8 ´ 10^–16)

D) AgBr (Ksp = 5.0 ´ 10^–13)

E)     PbI2 (Ksp = 6.5 ´ 10^–9)

50. Which salt has the highest molar solubility in pure water? Salt         Ksp

Cd(OH)2                5.3 ´ 10^–15

Fe(OH)2                 8.0 ´ 10^–16

PbCrO4                  1.8 ´ 10^–14

CdCO3                    6.2 ´ 10^–12

Mn(OH)2               2.0 ´ 10^–13

• • CdCO3
  • Cd(OH)2
  • Mn(OH)2
  • PbCrO4
  • Fe(OH)2

51. Which salt has the lowest molar solubility in pure water? Salt        Ksp

Cd(OH)2              5.3 ´ 10^–15

Fe(OH)2               8.0 ´ 10^–16

PbCrO4                1.8 ´ 10^–14

CdCO3                  6.2 ´ 10^–12

Mn(OH)2             2.0 ´ 10^–13

• • PbCrO4
  • Fe(OH)2
  • CdCO3
  • Cd(OH)2
  • Mn(OH)2

52. What is the hydroxide-ion concentration of a saturated solution of Ni(OH)2? For Ni(OH)2, Ksp = 2.0 ´ 10^–15. A) 2.8 ´ 10^–3 M

B)     7.9 ´ 10^–6 M

C)     1.0 ´ 10^–7 M

D)   2.7 ´ 10^–2 M

E)     1.6 ´ 10^–5 M

53. What is the pH of a saturated solution of Ni(OH)2? For Ni(OH)2, Ksp = 2.0 ´ 10^–15. A) 4.80

B)     8.90

C)     5.10

D)   9.20

E)     7.00

54. Rank the following salts in order of increasing molar solubility. Salt    Ksp

AgSCN              1.0 ´ 10^–12

Ag2CrO4          1.1 ´ 10^–12

Ag3PO4            1.0 ´ 10^–16

• • AgSCN < Ag2CrO4 < Ag3PO4
  • AgSCN < Ag3PO4 < Ag2CrO4
  • Ag3PO4 < Ag2CrO4 < AgSCN
  • Ag3PO4 < AgSCN < Ag2CrO4
  • Ag2CrO4 < AgSCN < Ag3PO4

55. The insoluble salts AV, B2W, C2X3, DY2, and EZ3, which were formed from the metal ions A⁺, B⁺, C³⁺, D²⁺, and E³⁺ and the nonmetals V^1–, W^2–, X^2–, Y^1–, and Z^1–, all have the same Ksp value. Which salt has the highest molar solubility?
    • AV
    • EZ3
    • DY2
    • B2W
    • C2X3

56. In which of the following solutions would silver(I) phosphate, Ag3PO4, be least soluble?
    • 0.10 M Na3PO4
    • 0.10 M AgNO3
    • 0.10 M Na2HPO4
    • 0.10 M HNO3
    • 0.10 M NaH2PO4

57. In which of these solutions would silver(I) carbonate have the lowest molar solubility? For silver(I) carbonate,

Ksp = 8.5 ´ 10^–12.

• • 0.03 M H2CO3
  • 0.1 M AgNO3
  • 0.01 M AgNO3
  • 0.1 M Na2CO3
  • pure water

58. The figure below represents the result of adding which of the following aqueous solutions to a filtered, saturated solution of AgCl?