Question 1

Which of the following statements best describes the trend shown in the plot of $$\Delta G^\circ$$ versus temperature for a chemical reaction, as shown in the provided figure?

Accepted Answer

$$\Delta H^\circ \u003e 0$$, $$\Delta S^\circ \u003c 0$$

Question 2

Given the reaction: FeO(s) + CO(g) $$\rightarrow CO$_2(g) + Fe(s$$), with $$\Delta H = -11.0 kJ $$and $$\Delta S = -17.4 J/K$$, above what temperature does this reaction become nonspontaneous?

Accepted Answer

632 K

Question 3

Which of the following processes has $$\Delta S \u003c 0$$?

Accepted Answer

All of the above processes have $$\Delta S \u003c 0$$

Question 4

For the reaction A(aq) + B(aq) $$\rightleftharpoons C(aq$$), $$\Delta G^\circ_{rxn} = -4.95 kJ/$$mol at 25$$^\circC. If$$ [A] = 0.30 M, [B] = 0.40 M, and [C] = 12.6 M, which of the following will occur?

Accepted Answer

More A and B are produced

Question 5

Which of the following has the largest entropy?

Accepted Answer

H$$_2O(g)$$

Question 6

Which of the following does NOT have a $$\Delta G^\circ$$ value of zero?

Accepted Answer

Br$$_2(l)$$

Question 7

Which statement is TRUE regarding entropy and thermodynamics?

Accepted Answer

Unlike enthalpy, we can know absolute values of $$S$$

Question 8

A container is filled with Ne gas. Which of the following changes would result in an increase in the entropy of the system?

Accepted Answer

All of the above

Question 9

Given the following reactions:

CO$$_2(g$$) $$\rightarrow C(s) + O$_2(g$$), $$\Delta G^\circ_{rxn} = +394.4 kJ
CO(g$$) + $$\frac{1}{2}O$_2(g$$) $$\rightarrow CO$_2(g$$), $$\Delta G^\circ_{rxn} = -257.2 kJ

$$Calculate $$\Delta G^\circ (kJ) $$for the reaction: CO(g) $$\rightarrow C(s$$) + $$\frac{1}{2}O$_2(g).$$

Accepted Answer

$$+137.2 kJ$$

Question 10

The standard molar entropy change of vaporization ($$\Delta S_{vap}) $$for CH$$_3OH(l$$) $$\rightarrow CH$_3OH(g) at $$its boiling point (337.8 K) is calculated using $$\Delta H_{vap} = 35.21 kJ/$$mol. What is $$\Delta S_{vap} in J/$$mol-K?

Accepted Answer

$$104.2 J/$$mol-K

Question 11

Which of the following best explains why the entropy of vaporization is greater than the entropy of fusion for most substances?

Accepted Answer

The transition from liquid to gas involves a much greater increase in molecular disorder than from solid to liquid.

Question 12

Using the data provided, calculate the standard entropy change ($$\Delta S^\circ) $$for the reaction: 2 CO(g) + O$$_2(g$$) $$\rightarrow 2 CO$_2(g).$$

Accepted Answer

$$31.4 J/K$$

Question 13

Which of the following best describes the effect of decreasing pressure on the vaporization of a liquid at constant temperature?

Accepted Answer

The Gibbs free energy change ($$\Delta G) $$for vaporization becomes more negative.

Question 14

Given the following standard free energies of formation at 25$$^\circC$$:
Ag$$^+(aq$$): $$77.11 kJ/$$mol
Br$$^-(aq$$): $$-102.8 kJ/$$mol
AgBr(s): $$-96.9 kJ/$$mol

Calculate $$\Delta G^\circ_{rxn}$$ for the dissolution of AgBr(s) $$\rightarrow Ag$^+(aq) + Br$^-(aq).$$

Accepted Answer

$$183.01 kJ/$$mol

Question 15

Which of the following is a correct application of the equation $$\Delta G = \Delta G^\circ + RT \ln Q$$?

Accepted Answer

It predicts the direction of a reaction under non-standard conditions.

Question 16

Which of the following elements, in their standard state, would have a standard entropy ($$S^\circ) of $$zero?

Accepted Answer

None of the above

Question 17

Which of the following best describes the physical meaning of the sign of $$\Delta G$$ for a process?

Accepted Answer

$$\Delta G \u003c 0$$ indicates a spontaneous process under the given conditions.

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