Question 1

Which statement best describes the First Law of Thermodynamics?

Accepted Answer

Energy cannot be created or destroyed; it can only be transformed from one form to another.

Question 2

A battery is recharged with 100 kJ of useful energy. According to the Second Law of Thermodynamics, which statement is correct?

Accepted Answer

More than 100 kJ is required because some energy is lost as heat to the surroundings.

Question 3

Which of the following best explains why melting ice is a spontaneous process above 0°C, even though it is endothermic?

Accepted Answer

The process increases the entropy of the system, which can drive spontaneity even when heat is absorbed.

Question 4

Which equation correctly relates entropy ($S$) to the number of microstates ($W$)?

Accepted Answer

$S = k \ln W$

Question 5

Consider the expansion of an ideal gas into an evacuated bulb. What happens when the valve is opened, and why?

Accepted Answer

Gas molecules move into the vacuum, increasing the entropy of the system because there are more possible microstates.

Question 6

Which of the following processes will have a positive entropy change ($\Delta S > 0$)?

Accepted Answer

Sublimation of solid carbon dioxide to carbon dioxide gas.

Question 7

Which factor does NOT generally increase the standard molar entropy ($S^\circ$) of a substance?

Accepted Answer

Decreasing the number of energetically equivalent microstates.

Question 8

For the reaction $2N_2O(g) \rightarrow 2N_2(g) + O_2(g)$, predict the sign of $\Delta S_{system}$.

Accepted Answer

Positive, because the number of gas molecules increases.

Question 9

Which statement about spontaneous processes is correct?

Accepted Answer

Spontaneous processes occur without ongoing outside intervention.

Question 10

Which equation defines the Gibbs free energy change ($\Delta G$) at constant temperature and pressure?

Accepted Answer

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

Question 11

A reaction has $\Delta H = -100$ kJ and $\Delta S = -200$ J/K. At what temperature will the reaction become nonspontaneous?

Accepted Answer

At temperatures above $500$ K.

Question 12

Which of the following statements about entropy and state changes is correct?

Accepted Answer

Liquids have higher entropy than solids, but lower than gases.

Question 13

Which process will result in a decrease in entropy ($\Delta S < 0$)?

Accepted Answer

Freezing of water.

Question 14

Which of the following is true about the relationship between $\Delta G$ and equilibrium constant $K$?

Accepted Answer

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

Question 15

Which of the following will increase the entropy of the surroundings?

Accepted Answer

An exothermic reaction at low temperature.

Question 16

Which of the following is NOT a standard state for a substance?

Accepted Answer

A pure liquid at 2 atm pressure.

Question 17

Which of the following statements about microstates and macrostates is correct?

Accepted Answer

The greater the number of microstates, the higher the entropy of the macrostate.

Question 18

For the reaction $N_2(g) + 3 H_2(g) \rightarrow 2 NH_3(g)$, what is the sign of $\Delta S_{system}$?

Accepted Answer

Negative, because the number of gas molecules decreases.

Question 19

Which of the following is the correct expression for the standard entropy change ($\Delta S^\circ$) of a reaction?

Accepted Answer

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

Chapter 19: Free Energy and Thermodynamics – Study Notes

Study Guide - Practice Questions