Exam 3

21. ΔS is negative for the reaction ___ [A] Mg(NO3)2(aq)+K2CO3(aq)→MgCO3(s)+2NaNO3(aq) [B] LiOH(aq)→Li+(aq)+OH−(aq) [C] C6H12O6(s)→6C(s)+6H2(g)+3O2(g) [D] 2NH3(g)→N2(g)+3H2(g) [E] CH3OH(l)→CH3OH(g)

[A] Mg(NO3)2(aq)+K2CO3(aq)→MgCO3(s)+2NaNO3(aq)

2. Consider the equilibrium B(aq)+H2O(l) ⇌HB+(aq)+OH−(aq). Suppose that a salt of HB+ is added to a solution of B at equilibrium [A] The concentration of B(aq) will increase [B] The concentration of B(aq) will decrease [C] The concentration of B(aq) will stay the same [D] The concentration of OH- will increase [E] The concentration of OH- will remain the same

[A] The concentration of B(aq) will increase

28. Which below best describe(s) the behavior of an amphoteric hydroxide in water? [A] With both conc. aq. NaOH and conc. aq. HCl, its suspension dissolves [B] With conc. aq. NaOH, its suspension dissolves. [C] With conc. aq. NaOH, its clear solution forms a precipitate. [D] With conc. aq. HCl, its clear solution forms a precipitate. [E] With conc. aq. HCl, its suspension dissolves

[A] With both conc. aq. NaOH and conc. aq. HCl, its suspension dissolves

17. Which one of the following processes produces a decrease in the entropy of the system? [A] deposition of solid CO2 from gaseous CO2 [B] mixing of two gases into one container [C] dissolution of KCl(s) in water [D] evaporation of Hg(l) to form Hg(g) [E] melting ice to form water

[A] deposition of solid CO2 from gaseous CO2

12. The thermodynamic quantity that expresses the extent of randomness in a system is __ [A] entropy [B] enthalpy [C] bond energy [D] heat flow [E] internal energy

[A] entropy

15. The second law of thermodynamics states that ________ [A] for any spontaneous process, the entropy of the universe increases [B] the entropy of a pure crystalline substance is zero at absolute zero [C] ΔH°rxn = ∑nΔH°f (products) - ∑mΔH°f (reactants) [D] ΔE = q + w [E] ΔS = q /T at constant temperature

[A] for any spontaneous process, the entropy of the universe increases

19. Consider a pure crystalline solid that is heated from absolute zero to a temperature above the boiling point of the liquid. Which of the following processes produces the greatest increase in the entropy of the substance? [A] vaporizing the liquid [B] heating the gas [C] melting the solid [D] heating the liquid [E] heating the solid

[A] vaporizing the liquid

14. Which one of the following is always positive when a spontaneous process occurs? [A] Δ Suniverse [B] Δ Ssystem [C] Δ Huniverse [D] Δ Hsurroundings [E] Δ Ssurroundings

[A] Δ Suniverse

The first law of thermodynamics can be given as ________ [A] ΔE=q+w [B] for any spontaneous process, the entropy of the universe increases [C] the entropy of a pure crystalline substance at absolute zero is zero [D] ΔS=qrev/T at constant temperature [E] ΔHºrxn=∑nΔHºf(products)−∑mΔHºf(reactants)

[A] ΔE=q+w

23. Δ S is positive for the reaction ________ [A] 2Hg (l) + O2 (g) → 2HgO (s) [B] BaF2 (s) → Ba2+ (aq) + 2F- (aq) [C] 2H2 (g) + O2 (g) → 2H2O (g) [D] 2NO2 (g) → N2O4 (g) [E] CO2 (g) → CO2 (s)

[B] BaF2 (s) → Ba2+ (aq) + 2F- (aq)

20. Which one of the following correctly indicates the relationship between the entropy of a system and the number of different arrangements, W, in the system? [A] S = kW [B] S = k lnW [C] S = Wk [D] S = k/W [E] S = W/k

[B] S = k lnW

7. Which of the following statements is true? [A] Processes that are spontaneous in one direction are spontaneous in the opposite Direction [B] Spontaneity can depend on the temperature [C] Processes are spontaneous because they occur at an observable rate [D] All of the statements are true [E] All of the statements are wrong

[B] Spontaneity can depend on the temperature

8. What change will be caused by addition of a small amount of HCl to a solution containing fluoride ions and hydrogen fluoride? [A] The fluoride ions will precipitate out of solution as its acid salt. [B] The concentration of fluoride ion will decrease and the concentration of hydrogen fluoride will increase. [C] The concentration of hydronium ions will increase significantly [D] The concentration of hydrogen fluoride will decrease and the concentration of fluoride ions will increase. [E] The concentration of fluoride ions will increase as will the concentration of hydronium ions.

[B] The concentration of fluoride ion will decrease and the concentration of hydrogen fluoride will increase.

Which of these statements about the common-ion effect is most correct? [A] Common ions alter the equilibrium constant for the reaction of an ionic solid with water. [B] The solubility of a salt MA is decreased in a solution that already contains either M+ or A− [C] The solubility of a salt MA is affected equally by addition of either A− or a non-common ion [D] The common-ion effect does not apply to unusual ions like SO32− [E] The solubility of a salt remains unaffected on addition of a common ion

[B] The solubility of a salt MA is decreased in a solution that already contains either M+ or A−

23. Of the five salts listed below, which has the highest concentration of its cation in water? Assume that all salt solutions are saturated and that the ions do not undergo any Additional reactions in water. [A] lead (II) chromate, Ksp = 2.8×10−13 [B] cobalt(II) hydroxide, Ksp = 1.3×10−15 [C] cobalt(II) sulfide, Ksp = 5×10−22 [D] chromium(III) hydroxide, Ksp = 1.6×10−30 [E] silver sulfide, Ksp = 6×10−51

[B] cobalt(II) hydroxide, Ksp = 1.3×10−15

12. In a solution, when the concentrations of a weak acid and its conjugate base are equal,.... [A] the system is not at equilibrium [B] the -log of the [H+] and the -log of the Ka are equal [C] the buffering capacity is significantly decreased [D] the buffering capacity is significantly increased [E] All of the above are true.

[B] the -log of the [H+] and the -log of the Ka are equal

5. When a system is at equilibrium, ________ [A] the reverse process is spontaneous but the forward process is not [B] the process is not spontaneous in either direction [C] both forward and reverse processes have stopped [D] the forward process is spontaneous but the reverse process is not [E] the forward and the reverse processes are both spontaneous

[B] the process is not spontaneous in either direction

2. A reversible change produces the maximum amount of ________ that can be achieved by the system on the surroundings [A] products [B] work [C] reactants [D] entropy [E] Enthalpy

[B] work

30. In which of the following aqueous solutions would you expect AgCl to have the lowest solubility? [A] pure water [B] 0.010 M KCl [C] 0.020 M LiCl [D] 0.015 M NaCl [E] 0.0050 M AgNO3

[C] 0.020 M LiCl

9. Which of the following solutions has the greatest buffering capacity? [A] 0.243 M HF and 0.192 M NaF [B] 0.485 M HF and 0.383 M NaF [C] 0.970 M HF and 0.766 M NaF [D] 0.160 M HF and 0.126 M NaF

[C] 0.970 M HF and 0.766 M NaF

8. The process of iron being oxidized to make iron(III) oxide (rust) is spontaneous. Which of these statements about this process is/are true? [A] The oxidation of iron is endothermic [B] The energy of the universe is decreased when iron is oxidized to rust [C] Equilibrium is achieved in a closed system when the rate of iron oxidation is equal to the rate of iron(III) oxide reduction [D] The reduction of iron(III) oxide to iron is also spontaneous [E] Because the process is spontaneous, the oxidation of iron must be fast

[C] Equilibrium is achieved in a closed system when the rate of iron oxidation is equal to the rate of iron(III) oxide reduction

11. The addition of hydrofluoric acid and ________ to water produces a buffer solution [A] HF [B] KI [C] NaF [D] NaBr [E] NaNO3

[C] NaF

33. Under what conditions does an ionic compound precipitate from a solution of the constituent ions? [A] When Q = Ksp [B] Always [C] When Q exceeds Ksp [D] When Q is less than Ksp [E] Never

[C] When Q exceeds Ksp

16. Which of these expressions correctly expresses the solubility-product constant for Ag3PO4 in water? [A] [Ag][PO4] [B] [Ag+][PO43−] [C] [Ag+]3[PO43−] [D] [Ag+][PO43−]3 [E] [Ag+]3[PO43−]3

[C] [Ag+]3[PO43−]

13. For an isothermal process, Δ S = ________ [A] Tqrev [B] q [C] qrev/T [D] q + w [E] qrev

[C] qrev/T

3. A reaction that is spontaneous ________ [A] is very slow [B] has an equilibrium position that lies far to the left [C] will proceed without outside intervention [D] is also spontaneous in the reverse direction [E] is very rapid

[C] will proceed without outside intervention

6. A reversible process is one that ________ [A] must be carried out at high temperature [B] must be carried out at low temperature [C] happens spontaneously [D] can be reversed with no net change in either system or surroundings [E] is spontaneous in both directions

[D] can be reversed with no net change in either system or surroundings

16. In a particular spontaneous process the entropy of the system decreases. What can you conclude about the sign and magnitude of ΔSsurr? [A] ΔSsurr is negative and greater than the magnitude of the decrease in ΔSsys [B] ΔSsurr is positive and less than the magnitude of the decrease in ΔSsys. [C] ΔSsurr is negative and less than the magnitude of the decrease in ΔSsys. [D] ΔSsurr is positive and greater than the magnitude of the decrease in ΔSsys. [E] ΔSsurr is positive and equal to the magnitude of the decrease in ΔSsys

[D] ΔSsurr is positive and greater than the magnitude of the decrease in ΔSsys.

29. In which aqueous system is PbI2 least soluble? [A] 0.5 M HI [B] H2O [C] 1.0 M HNO3 [D] 0.2 M HI [E] 0.8 M KI

[E] 0.8 M KI

22. Of the following, the entropy of ________ is the largest [A] HBr (g) [B] HCl (l) [C] HCl (g) [D] HCl (s) [E] HI (g)

[E] HI (g)

32. In nonaqueous solvents, it is possible to react HF to create H2F+. Which of these statements follows from this observation? I HF can act like a strong acid in nonaqueous solvents. II HF can act like a base in nonaqueous solvents. III HF is thermodynamically unstable IV There is an acid in the nonaqueous medium that is a stronger acid than HF [A] I and II [B] I and III [C] I and IV [D] II and III [E] II and IV

[E] II and IV

18. Which one of the following processes produces a decrease of the entropy of the system? [A] boiling of alcohol [B] sublimation of naphthalene [C] explosion of nitroglycerine [D] dissolving sodium chloride in water [E] dissolving oxygen in water

[E] dissolving oxygen in water

10. The Henderson-Hasselbalch equation is ________ [A] pH = pKa + log [acid]/[base] [B] [H+] = Ka + [base]/[acid] [C] pH = log [acid]/[base] [D] pH = pKa - log [base]/[acid] [E] pH = pKa + log [base]/[acid]

[E] pH = pKa + log [base]/[acid]

4. Of the following, only ________ is not a state function. [A] H [B] E [C] S [D] T [E] q

[E] q