Question 1

Which of the following best describes a spontaneous process in thermodynamics?

Accepted Answer

A process that occurs without ongoing outside intervention.

Question 2

Which of the following transitions results in an increase in entropy ($$\Delta S \u003e 0$$)?

Accepted Answer

$$\mathrm{H_2O\ (l) \rightarrow H_2O\ (g)}$$

Question 3

Which of the following correctly lists the states of matter in order of increasing entropy?

Accepted Answer

Solid \u003c Liquid \u003c Gas

Question 4

Given the reaction $$\mathrm{C_3H_8\ (g) + 5\ O_2$\ (g) \rightarrow 3\ CO_2$\ (g) + 4\ H_2O\ (g)}$$ with $$\Delta H_{rxn} = -2044\ \mathrm{kJ} at$$ $$25^\circ\mathrm{C}$$, what is the sign of the entropy change of the surroundings ($$\Delta S_{surr}$$)?

Accepted Answer

Positive

Question 5

Which equation correctly relates the change in entropy of the surroundings to the enthalpy change of a reaction?

Accepted Answer

$$\Delta S_{surr} = -\dfrac{\Delta H_{sys}}{T}$$

Question 6

Which of the following best defines entropy ($$S$$)?

Accepted Answer

A measure of the disorder or randomness of a system.

Question 7

For the reaction $$\mathrm{$$CCl_4$$\ (g) \rightarrow C\ (s, graphite) + 2\ Cl_2$\ (g)}$$ with $$\Delta H = +95.7\ \mathrm{kJ}$$ and $$\Delta S = +142.2\ \mathrm{J/K}$$, calculate $$\Delta G at$$ $$25^\circ\mathrm{C}$$ and determine if the reaction is spontaneous.

Accepted Answer

$$\Delta G = +53.1\ \mathrm{kJ}$$; not spontaneous

Question 8

Which of the following statements about Gibbs free energy ($$G) is $$correct?

Accepted Answer

A negative $$\Delta G$$ indicates a spontaneous process at constant temperature and pressure.

Question 9

Which of the following reactions is expected to have a positive entropy change ($$\Delta S \u003e 0$$)?

Accepted Answer

$$\mathrm{2\ N_2O\ (g) \rightarrow 2\ N_2$\ (g) + O_2$\ (g)}$$

Question 10

Which of the following best describes the relationship between temperature and entropy?

Accepted Answer

As temperature increases, entropy increases.

Question 11

Which equation is used to calculate the standard entropy change for a reaction ($$\Delta S^\circ_{rxn}$$)?

Accepted Answer

$$\Delta S^\circ_{rxn} = \sum n S^\circ_{products} - \sum n S^\circ_{reactants}$$

Question 12

Which of the following trends is correct regarding standard molar entropy ($$S^\circ$$)?

Accepted Answer

For a given state, $$S^\circ$$ increases with increasing molar mass.

Question 13

Which of the following correctly relates the standard free energy change ($$\Delta G^\circ_{rxn}) to $$the equilibrium constant ($$K) at $$temperature $$T$$?

Accepted Answer

$$\Delta G^\circ_{rxn} = -RT \ln K$$

Question 14

A reaction has $$\Delta H \u003c 0$$ and $$\Delta S \u003c 0. $$Under what temperature conditions will this reaction be spontaneous?

Accepted Answer

At low temperatures

Question 15

Which of the following is true about reversible and irreversible reactions?

Accepted Answer

A reversible reaction can proceed in both the forward and reverse directions under the same conditions.

Question 16

For the reaction $$\mathrm{SO_2$\ (g) + \frac{1}{2} O_2$\ (g) \rightarrow SO_3$\ (g)}$$, which of the following is the correct expression for the standard free energy change ($$\Delta G^\circ_{rxn}) $$using standard free energies of formation ($$\Delta G^\circ_f$$)?

Accepted Answer

$$\Delta G^\circ_{rxn} = \Delta G^\circ_f (SO_3$) - [\Delta G^\circ_f (SO_2$) + \frac{1}{2} \Delta G^\circ_f (O_2$)]$$

Question 17

Which of the following statements about the standard free energy of formation ($$\Delta G^\circ_f) is $$correct?

Accepted Answer

$$\Delta G^\circ_f$$ for any element in its standard state is zero.

Question 18

A reaction has $$\Delta H \u003e 0$$ and $$\Delta S \u003e 0. At $$what temperature will the reaction become spontaneous?

Accepted Answer

At high temperatures

Question 19

Which of the following best describes the free energy change of a reaction under nonstandard conditions?

Accepted Answer

$$\Delta G = \Delta G^\circ + RT \ln Q$$

General Chemistry II – Thermodynamics & Free Energy Study Guide

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