Question

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

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

Answer 1

The correct option is E $Q$ is greater than one and $△G$ is less than zero

We know,

$△G=△G^{\circ }+RTlnQ$

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

and $E^{\circ }>0$

$\therefore △G^{\circ }<0$

or $△G-RTlnQ<0$

It is possible when $Q>1$, and $△G<0$.