Chemical and Ionic Equilibrium - Result Question 1

####1. The incorrect match in the following is (2019 Main, 12 April II)

(a) $\Delta G^{\circ}<0, K>1$

(b) $\Delta G^{\circ}=0, K=1$

(c) $\Delta G^{\circ}>0, K<1$

(d) $\Delta G^{\circ}<0, K<1$

Show Answer

Answer:

Correct Answer: 1. (d)

Solution:

  1. The incorrect match is $\Delta G^{\circ}<0, K<1$.

For an ideal gas $\Delta G^{\circ}=-R T \ln K$.

$\therefore \quad \ln K=-\frac{\Delta G^{\circ}}{R T}$ and $K=e^{-\Delta G^{\circ} / R T}$

The above equation is helpful in predicting the spontaneity of the reaction. e.g.

(i) If $\Delta G^{\circ}<0,-\Delta G^{\circ} / R T=+$ ve and $e^{-\Delta G^{\circ} / R T}>1$ and hence, $K>1$. It means that the reaction occur spontaneously in the forward direction or products predominate over reactants.

(ii) If $\Delta G^{\circ}>0 ;-\Delta G^{\circ} / R T=-$ ve and $e^{-\Delta G^{%} R T}<1$ and hence, $K<1$. It means that the reaction is non-spontaneous in forward direction (i.e. product side) but spontaneous in reverse direction (i.e. reactants predominate over products or the reaction occurs rarely).

(iii) When $K=1$, then $\Delta G^{\circ}=0$. This situation generally occur at equilibrium.



NCERT Chapter Video Solution

Dual Pane