Q: Which statement is correct regarding spontaneity and $\Delta G$?

If $\Delta G < 0$, then the reaction is spontaneous as written.

Q: Which of the following statements about entropy ($\Delta S$) is correct?

Entropy increases when a solid melts to a liquid.

Q: Which of the following is a correct statement about Gibbs free energy ($\Delta G$)?

$\Delta G$ is always negative for spontaneous reactions.

Q: Which of the following is true for a process where $\Delta H > 0$ and $\Delta S < 0$?

The process is nonspontaneous at all temperatures.

Q: Which of the following is a correct expression for the Gibbs free energy change?

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

Question 1

How much energy in joules is contained in a candy bar having 195 Calories? (Note: $1 	ext{ Calorie} = 4184 	ext{ J}$)

Accepted Answer

$8.16 	imes 10^5 	ext{ J}$

Question 2

By what factor is the electrostatic potential energy between the ions in MgO greater than that between the ions in NaF? Assume the distance between nuclei is the same in both compounds.

Accepted Answer

$4 	imes$

Question 3

Which of the following is a form of kinetic energy?

Accepted Answer

Thermal energy

Question 4

A reaction has $\Delta H = 242 	ext{ kJ/mol}$ and $\Delta S = 447 	ext{ J/K mol}$. At what temperature does the reaction become spontaneous? (Assume $\Delta G = 0$ at the threshold of spontaneity.)

Accepted Answer

$423^\circ 	ext{C}$

Question 5

Which statement is correct regarding spontaneity and $\Delta G$?

Accepted Answer

If $\Delta G < 0$, then the reaction is spontaneous as written.

Question 6

Which of the following processes is endothermic?

Accepted Answer

Melting of ice

Question 7

Which of the following statements about entropy ($\Delta S$) is correct?

Accepted Answer

Entropy increases when a solid melts to a liquid.

Question 8

A gas expands from 1.0 L to 5.0 L against a constant external pressure of 2.0 atm. What is the work done by the gas? ($1 	ext{ L atm} = 101.3 	ext{ J}$)

Accepted Answer

$-810.4 	ext{ J}$

Question 9

Which of the following changes will result in a positive $\Delta S$ for the system?

Accepted Answer

Dissolving salt in water

Question 10

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

Accepted Answer

The reaction is spontaneous at all temperatures.

Question 11

A chemical reaction has $\Delta H = 154 	ext{ kJ}$ and $\Delta S = 154 	ext{ J/K}$. At what temperature (in K) does the reaction become spontaneous?

Accepted Answer

$1576 	ext{ K}$

Question 12

Which of the following is NOT a state function?

Accepted Answer

Work

Question 13

Which of the following statements about the first law of thermodynamics is correct?

Accepted Answer

Energy is conserved in all physical and chemical processes.

Question 14

Which of the following processes involves a decrease in entropy?

Accepted Answer

Condensation of steam

Question 15

A sample of gas at 1.00 atm and 273 K occupies 22.4 L. If the pressure is increased to 2.00 atm at constant temperature, what is the new volume?

Accepted Answer

$11.2 	ext{ L}$

Question 16

Which of the following best describes the change in enthalpy ($\Delta H$) for an exothermic reaction?

Accepted Answer

$\Delta H < 0$

Question 17

Which of the following is a correct statement about Gibbs free energy ($\Delta G$)?

Accepted Answer

$\Delta G$ is always negative for spontaneous reactions.

Question 18

Which of the following is a correct unit for entropy?

Accepted Answer

$	ext{J/K mol}$

Question 19

Which of the following is true for a process where $\Delta H > 0$ and $\Delta S < 0$?

Accepted Answer

The process is nonspontaneous at all temperatures.

Question 20

Which of the following is a correct expression for the Gibbs free energy change?

Accepted Answer

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

General Chemistry: Energy Conversion and Electrostatic Potential in Ionic Compounds

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