ACS CP Thermodynamics & Chemical Kinetics

Question 1

For a reaction at standard conditions with ΔG° = -20.0 kJ/mol at 298 K, what is the equilibrium constant K? (R = 8.314 J/mol·K)

Accepted Answer

K ≈ 2,960

Answer

K ≈ 0.000338

Answer

K ≈ 8.07

Answer

K ≈ 0.124

Question 2

Which thermodynamic state function represents the maximum non-expansion work obtainable from a process at constant temperature and pressure?

Accepted Answer

Gibbs free energy (G)

Answer

Enthalpy (H)

Answer

Helmholtz free energy (A)

Answer

Internal energy (U)

Question 3

According to Hess's Law, the standard enthalpy change of a reaction is:

Accepted Answer

Independent of the pathway taken

Answer

Equal to the activation energy of the forward reaction

Answer

Always negative for all spontaneous reactions

Answer

Dependent only on the physical state of the products

Question 4

For an ideal gas expanding isothermally and reversibly, which relationship correctly applies the First Law of Thermodynamics?

Accepted Answer

q = -w and ΔU = 0

Answer

ΔU > 0 and q = 0

Answer

ΔH < 0 and w = 0

Answer

ΔS = 0 and ΔG = 0

Question 5

The Clausius-Clapeyron equation is primarily used to relate which two properties during phase transitions?

Accepted Answer

Vapor pressure and temperature

Answer

Pressure and volume at constant temperature

Answer

Entropy change and heat capacity

Answer

Free energy and reaction quotient

Question 6

For an exothermic reaction at equilibrium, Le Chatelier's principle predicts that increasing temperature will:

Accepted Answer

Shift equilibrium to the left, increasing reactant concentrations

Answer

Shift equilibrium to the right, producing more products

Answer

Have no effect on the equilibrium position

Answer

Increase K while decreasing the reaction rate

Question 7

Which of the following correctly expresses the Gibbs-Helmholtz relationship at constant pressure?

Accepted Answer

ΔG = ΔH - TΔS

Answer

ΔG = ΔH + TΔS

Answer

ΔG = ΔU - TΔS

Answer

ΔG = ΔH + PΔV