Question

Which of the following lines correctly show the temperature dependence of equilibrium constant K, for an exothermic reaction?

• A. A and D
• B. A and B
• C. B and C
• D. C and D

Answer 1

The correct option is B A and B

We know, $\Delta G^0=-RTlnK$
$\Rightarrow \Delta H^0-T\Delta S^0=-RTlnK$
$\Rightarrow -\frac{\Delta H^0}{RT}+\frac{\Delta S^0}{R}=lnK$
From this equation, the slope of the graph of $lnK$ vs $\frac{1}{T}$ is $-\frac{\Delta H^0}{R}$, but since it is an exothermic reaction, the slope should be positive.
Hence the lines that correctly show the temperature dependence of equilibrium constant K, for an exothermic reaction are A and B.