Question

Which of the following options will be correct for the stage of half completion of the reaction $A\rightleftharpoons B$

• A. $\Delta G^{\Theta }=0$
• B. $\Delta G^{\Theta }>0$
• C. $\Delta G^{\Theta }=-RTln2$
• D. $\Delta G^{\Theta }<0$

Answer 1

The correct option is A $\Delta G^{\Theta }=0$

Given reaction $A\rightleftharpoons B$ and we need to find $\Delta G^{\Theta }$.

So, formula which can be used is

$\Delta G^{\Theta }=-RTlnK$

Since at half stage completion,

$\left[A\right]=\left[B\right]$

$K=\frac{\left[product\right]}{\left[reactant\right]}=\frac{\left[B\right]}{\left[A\right]}=1$

As for $50\%$ completion both product and reactant will have equal concentration.

$ln\left(K\right)=ln\left(1\right)=0$

$\therefore \Delta G^{\Theta }=-RT\left(0\right)$

Therefore, the correct answer is (A) i.e.,

$\Delta G^{\Theta }=0$.