Question

When the total cell emf of a voltaic cell is greater than zero, which of the following is true about the reaction quotient $Q$ and free energy change $\Delta G$ for the cell reaction?

• A. $Q$ is less than one and $\Delta G$ is greater than zero
• B. $Q$ is greater than one and $\Delta G$ is greater than zero
• C. $Q$ is less than one and $\Delta G$ is less than zero
• D. $Q$ is zero and $\Delta G$ is greater than zero
• E. $Q$ is greater than one and $\Delta G$ is less than zero

Answer 1

Answer: (E)

$\Delta G=\Delta G^{\circ }+RT$ In $Q$

$\because \Delta G^{\circ }=-nF{E}^{\circ }$

and $E^{\circ }>0$

$\therefore \Delta G^{\circ }<0$

or $\Delta G-RT$ In $Q<0$

is possible when $Q>1$, and $\Delta G<0$