Free energy and equilibrium Knowledge-Based Download PDF

Questions

1. 1.

   When all stoichiometric coefficients in a balanced reversible chemical equation are multiplied by a factor of 2 at constant temperature, how do the standard Gibbs free energy change ($\Delta G^\circ$) and the equilibrium constant ($K$) change?

   • A) $\Delta G^\circ$ remains unchanged, and $K$ is squared.
   • B) $\Delta G^\circ$ is doubled, and $K$ is doubled.
   • C) $\Delta G^\circ$ is doubled, and $K$ is squared.
   • D) $\Delta G^\circ$ is squared, and $K$ is doubled.
2. 2.

   According to the thermodynamic relationship $\Delta G = \Delta G^\circ + RT \ln Q$, under which condition is the actual Gibbs free energy change of a reaction ($\Delta G$) equal to its standard Gibbs free energy change ($\Delta G^\circ$)?

   • A) When the system reaches chemical equilibrium such that $Q = K$
   • B) When the standard Gibbs free energy change is zero ($\Delta G^\circ = 0$)
   • C) When the reaction quotient equals 1 ($Q = 1$)
   • D) When the equilibrium constant of the reaction equals 1 ($K = 1$)
3. 3.

   For an endothermic reaction that proceeds with an increase in standard entropy ($\Delta H^\circ > 0$ and $\Delta S^\circ > 0$), how do the standard Gibbs free energy change ($\Delta G^\circ$) and the equilibrium constant ($K$) change as the temperature of the system is increased?

   • A) $\Delta G^\circ$ increases and $K$ decreases.
   • B) $\Delta G^\circ$ increases and $K$ increases.
   • C) $\Delta G^\circ$ decreases and $K$ increases.
   • D) $\Delta G^\circ$ decreases and $K$ decreases.
4. 4.

   For a reversible reaction at constant temperature $T$, the reaction quotient is measured to be greater than the equilibrium constant ($Q > K$). Which statement correctly describes the sign of the actual Gibbs free energy change ($\Delta G$) for the forward reaction and the direction in which the system proceeds spontaneously?

   • A) $\Delta G < 0$, and the forward reaction proceeds spontaneously.
   • B) $\Delta G = 0$, and the system is already at dynamic chemical equilibrium.
   • C) $\Delta G < 0$, and the reverse reaction proceeds spontaneously.
   • D) $\Delta G > 0$, and the reverse reaction proceeds spontaneously.
5. 5.

   A chemical reaction conducted at constant temperature $T$ has a negative standard Gibbs free energy change ($\Delta G^\circ < 0$). Which statement correctly describes the equilibrium constant ($K$) and the actual Gibbs free energy change ($\Delta G$) of the system once dynamic chemical equilibrium is established?

   • A) $K > 1$ and $\Delta G = 0$
   • B) $K < 1$ and $\Delta G = 0$
   • C) $K > 1$ and $\Delta G < 0$
   • D) $K = 1$ and $\Delta G < 0$