Question

For a reaction, $A_{\left(g\right)}\rightleftharpoons B_{\left(g\right)}$ at equilibrium the partial pressure of $B$ is found to be one-fourth of the partial pressure of $A$. The value of $\Delta G^0$ of the reaction $A\to B$ is:

• A. $RTln4$
• B. $-RTln4$
• C. $RTlog4$
• D. $-RTlog4$

Answer 1

Answer: (A)

$RTln4$

Reaction:

$A\left(g\right)\rightleftharpoons B\left(g\right)$

Let the partial pressure of $A$ be $P$.

$\therefore$ Partial pressure of $B=\frac{P}{4}$

$\therefore K_p=\frac{P/4}{P}=\frac{1}{4}$

$\Delta G^{\circ }=-RTln{K}_p=-RTIn\left(1/4\right)=RTln4$.