Question 1

Which of the following best describes the concept of entropy as illustrated by the image of a disordered pile of playing cards?

Accepted Answer

Entropy is a measure of the disorder or randomness in a system.

Question 2

According to the second law of thermodynamics, which of the following statements is true?

Accepted Answer

The entropy of the universe is constantly increasing.

Question 3

Which process would result in a negative entropy change ($$\Delta S \u003c 0$$)?

Accepted Answer

Water vapor condensing to form liquid water.

Question 4

Given the reaction: $$2SO_2(g) + O_2$(g) \rightarrow 2SO_3(g)$$, and the following standard molar entropies: $$SO_2(g$$): 248.1\ J/K\cdot mol$$, O_2$(g): 205.3\ J/K\cdot mol$$, $$SO_3(g$$): 256.6\ J/K\cdot mol$$, calculate $$\Delta S^\circ_{rxn}$$ at 25°C.

Accepted Answer

$$-188.3\ J/K$$

Question 5

Which of the following scenarios would have the greatest increase in entropy?

Accepted Answer

$$CO_2(s$$) \rightarrow $$CO_2(g$$)$$

Question 6

For the reaction $$Sb_2S_3(s) + 3Fe(s) \rightarrow 2Sb(s) + 3FeS(s)$$ with $$\Delta H = -125\ kJ at 25$$°C, what is $$\Delta S_{surr}$$?

Accepted Answer

$$-2.61 	imes 10^3$\ J/K$$

Question 7

Which equation correctly relates Gibbs free energy, enthalpy, and entropy?

Accepted Answer

$$\Delta G = \Delta H - T\Delta S$$

Question 8

A reaction has $$\Delta H  0. $$What can be concluded about its spontaneity?

Accepted Answer

It is spontaneous at all temperatures.

Question 9

Calculate the thermodynamic boiling point of water given $$\Delta H_{vap} = 44\ kJ$$ and $$\Delta S_{vap} = 118.8\ J/K.$$

Accepted Answer

$$373\ K$$

Question 10

Which of the following best explains why a highly exothermic reaction can be spontaneous even if the system's entropy decreases?

Accepted Answer

The large negative $$\Delta H$$ increases the entropy of the surroundings enough to make $$\Delta S_{universe}$$ positive.

Question 11

Which of the following equations is used to calculate the standard free energy change from the equilibrium constant?

Accepted Answer

$$\Delta G^\circ = -RT\ln K$$

Question 12

For the reaction $$C_{diamond}(s) \rightarrow C_{graphite}(s)$$, given $$\Delta G^\circ$$ for $$C_{diamond}(s) + O_2$(g) \rightarrow CO_2$(g) is$$ $$-397\ kJ$$ and for $$C_{graphite}(s) + O_2$(g) \rightarrow CO_2$(g) is$$ $$-394\ kJ$$, what is $$\Delta G^\circ$$ for the conversion?

Accepted Answer

$$-3\ kJ$$

Question 13

Which of the following best describes a reversible process as illustrated by the battery and starter motor diagram?

Accepted Answer

A process where the universe is unchanged after the cycle.

Question 14

Which of the following is true about the entropy change when a gas escapes from a solvent?

Accepted Answer

Entropy increases because the system becomes more disordered.

Question 15

Given the equation $$\Delta G = \Delta G^\circ + RT\ln Q$$, what does $$Q$$ represent?

Accepted Answer

The reaction quotient, which is the ratio of product to reactant concentrations at any point.

Question 16

Which of the following best explains why the entropy of a substance increases as it changes from solid to liquid to gas?

Accepted Answer

The number of possible arrangements increases.

Question 17

If $$\Delta G$$ for a reaction is positive, what does this indicate about the reaction under standard conditions?

Accepted Answer

The reaction is nonspontaneous.

Question 18

Which of the following is the correct relationship between Gibbs free energy and the maximum work obtainable from a system at constant temperature and pressure?

Accepted Answer

$$\Delta G = w_{max}$$

Question 19

Which of the following best describes the entropy change when a pure solid dissolves in water?

Accepted Answer

Entropy increases because the ions become more disordered.

Question 20

Which of the following is true for a reaction where $$\Delta H \u003e 0$$ and $$\Delta S \u003e 0$$?

Accepted Answer

The reaction is spontaneous only at high temperatures.

Thermodynamics: Entropy and Free Energy in Chemical Reactions

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