Question 1

Which of the following statements best describes the First Law of Thermodynamics?

Accepted Answer

Energy can be converted from one form to another, but is neither created nor destroyed.

Question 2

A chemical reaction occurs in a closed system at constant pressure and releases heat to the surroundings. Which of the following is true about the enthalpy change ($$\Delta H) $$and the type of reaction?

Accepted Answer

$$\Delta H is $$negative; the reaction is exothermic.

Question 3

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

Accepted Answer

$$\Delta E = q + w$$

Question 4

Which of the following processes is spontaneous and endothermic under standard conditions?

Accepted Answer

Melting of ice at 0$$^\circC$$

Question 5

Given the reaction: $$2H_2(g) + O_2$(g) \rightarrow 2H_2O(l)$$, which of the following is true about the standard enthalpy of formation ($$\Delta H_f^\circ) $$for $$H_2O(l)$$?

Accepted Answer

$$\Delta H_f^\circ$$ for $$H_2O(l) is $$negative because the formation of water from its elements releases energy.

Question 6

Which of the following best explains why the expansion of a gas into a vacuum is spontaneous?

Accepted Answer

Because the process increases the entropy of the system.

Question 7

Which of the following is a state function?

Accepted Answer

Enthalpy ($$H)$$

Question 8

A reaction has $$\Delta H = +40 kJ $$and $$\Delta S = +120 J/K. At $$what minimum temperature (in K) will this reaction become spontaneous?

Accepted Answer

Above $$333 K$$

Question 9

Which of the following correctly expresses the relationship between the standard free energy change ($$\Delta G^\circ) $$and the equilibrium constant ($$K$$)?

Accepted Answer

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

Question 10

Which of the following factors will increase the entropy ($$S) of a $$system?

Accepted Answer

Dissolving a solid into a solution

Question 11

Which of the following is true about the standard molar entropy ($$S^\circ) of a $$substance?

Accepted Answer

$$S^\circ is $$always positive and depends on the number of ways a substance can store energy.

Question 12

Which of the following equations is used to calculate the entropy change of the surroundings ($$\Delta S_{surr}) $$for a reaction at constant pressure?

Accepted Answer

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

Question 13

Which of the following statements about spontaneous processes is correct?

Accepted Answer

All spontaneous processes increase the entropy of the universe.

Question 14

Which of the following best describes the difference between a macrostate and a microstate?

Accepted Answer

A macrostate is defined by observable properties like P, V, and T, while a microstate is a specific arrangement of particles at a given instant.

Question 15

Which of the following is NOT a qualitative factor that increases the entropy of a system?

Accepted Answer

Decreasing the volume available to the system

Question 16

A reaction has $$\Delta H = -100 kJ $$and $$\Delta S = -200 J/K. At $$what temperature (in K) does the reaction change from spontaneous to nonspontaneous?

Accepted Answer

500 K

Question 17

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

Accepted Answer

$$\Delta G is $$zero at equilibrium.

Question 18

Which of the following is true about the relationship between kinetics and thermodynamics?

Accepted Answer

Thermodynamics determines if a reaction will occur, while kinetics determines how fast it occurs.

Question 19

Which of the following is the correct formula for calculating the standard entropy change ($$\Delta S^\circ_{rxn}) $$for a reaction?

Accepted Answer

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

Question 20

A reaction has $$\Delta G^\circ = -25 kJ at 298 K. $$What can you conclude about the equilibrium constant $$K$$ for this reaction?

Accepted Answer

$$K \u003e 1$$

Chapter 19: Free Energy and Thermodynamics – Study Notes

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