Q: The Second Law of Thermodynamics states that for any spontaneous process in an isolated system:

$$\Delta S_{\text{total}} \u003e 0$$

Q: The standard entropy change for a reaction is calculated as:

$$\Delta S^\circ = \sum S_{\text{products}} - \sum S_{\text{reactants}}$$

Question 1

Which of the following best describes the main limitation of classical thermodynamics?

Accepted Answer

It cannot explain the microscopic reasons for observed macroscopic behavior.

Question 2

A system that can exchange energy but not matter with its surroundings is called:

Accepted Answer

A closed system

Question 3

Which equation correctly relates the change in internal energy ($$\Delta U) to $$heat ($$q) $$and work ($$w$$)?

Accepted Answer

$$\Delta U = w + q$$

Question 4

If a chemical reaction at constant pressure releases heat and $$\Delta H \u003c 0$$, which term best describes the process?

Accepted Answer

Exothermic

Question 5

For a process where a gas expands against a constant external pressure, which equation gives the work done by the system?

Accepted Answer

$$w = -P \Delta V$$

Question 6

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

Accepted Answer

Entropy is a state function and measures disorder.

Question 7

The Second Law of Thermodynamics states that for any spontaneous process in an isolated system:

Accepted Answer

$$\Delta S_{	ext{total}} \u003e 0$$

Question 8

Which of the following is the correct expression for the change in Gibbs free energy ($$\Delta G$$)?

Accepted Answer

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

Question 9

A reaction has $$\Delta H = -50 kJ/$$mol and $$\Delta S = -100 J/($$mol·K). At what temperature (in K) does the reaction become non-spontaneous?

Accepted Answer

500 K

Question 10

The standard entropy change for a reaction is calculated as:

Accepted Answer

$$\Delta S^\circ = \sum S_{	ext{products}} - \sum S_{	ext{reactants}}$$

Question 11

Which of the following best describes a spontaneous process?

Accepted Answer

A process that occurs naturally without the need for work input

Question 12

The Third Law of Thermodynamics states that:

Accepted Answer

The entropy of a perfect crystal at absolute zero is zero.

Question 13

Given $$\Delta G = -30 kJ/$$mol, $$\Delta S = +70 J/($$mol·K), and $$T = 298 K $$for a reaction, what is the value of $$T\Delta S + \Delta H$$?

Accepted Answer

-9.14 kJ/mol (since $$T\Delta S = 20.86 kJ/$$mol, $$\Delta H = -9.14 kJ/$$mol)

Question 14

Which of the following is true about the relationship between the reaction quotient ($$Q$$), equilibrium constant ($$K$$), and Gibbs free energy ($$\Delta G$$)?

Accepted Answer

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

Question 15

At equilibrium, which of the following is true?

Accepted Answer

$$Q = K$$ and $$\Delta G = 0$$

Question 16

Which of the following best describes the difference between heat ($$q) $$and work ($$w$$)?

Accepted Answer

Heat is energy dispersed as random motion, work as non-random motion.

Question 17

For a gas, the relationship between heat capacities at constant pressure ($$C_p) $$and constant volume ($$C_v) is$$:

Accepted Answer

$$C_p = C_v + nR$$

Question 18

Which of the following statements about enthalpy ($$H) is $$correct?

Accepted Answer

Enthalpy is defined as $$H = U + PV$$

Question 19

A process occurs at constant pressure with only $$PV$$ work. Which equation correctly relates $$\Delta H$$, $$\Delta U$$, and $$P\Delta V$$?

Accepted Answer

$$\Delta H = \Delta U + P\Delta V$$

Thermodynamics: Principles, Laws, and Applications

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