Question

If the $E_{cell}^{\circ }$ for a given reaction has a negative value, which gives the correct relationships for the values of $\Delta G^{\circ }$ and $K_{eq}$?

• A. $\Delta G^{\circ }>0;K_{eq}<1$
• B. $\Delta G^{\circ }>0;K_{eq}>1$
• C. $\Delta G^{\circ }<0;K_{eq}>1$
• D. $\Delta G^{\circ }<0;K_{eq}<1$

Answer 1

The correct option is A $\Delta G^{\circ }>0;K_{eq}<1$

The equation is : $\Delta G=\Delta G^{\circ }RTlnK$

At equilibrium, $\Delta G=0$

$\therefore \Delta G^{\circ }=-RTlnK$ ---------------i

But $\Delta G^{\circ }=-nF{E}_{cell}^{\circ }$

Therefore, if $E_{cell}^{\circ }$ <0 then $\Delta G^{\circ }>0$

Also, by equation i, if $\Delta G^{\circ }>0$ then $K_{eq}<1$