Question

In an equilibrium reaction, for which $ \Delta {G^ \circ } = 0 $ , the equilibrium constant $ K $ should be equal to:
(A) Zero
(B) $ 10 $
(C) $ 1 $
(D) $ 2 $

Answer 1

Hint :A reaction that is non-spontaneous will have a positive $ \Delta {G^ \circ } $ and a small $ K $ value. When $ \Delta {G^ \circ } $ is equal to zero and $ K $ is around one, the reaction is said to be at equilibrium. The value of $ K $ depends on temperature.

Complete Step By Step Answer:
The value of the equilibrium constant for any reaction is calculated from the experiment. It depends on the temperature of the reaction because equilibrium is defined as a condition resulting from the rates of forward and reverse reactions being equal. As activities are unit less, they eliminate the units of all the quantities in the expression of equilibrium constant and make the constant itself unit less. If the forward reaction is endothermic, then by increasing the temperature we can increase the value of the equilibrium constant. The position of equilibrium changes if the temperature is changed. The equilibrium constant is very important because it tells us where the equilibrium lies.
In an equilibrium reaction, for which $ \Delta {G^ \circ } = 0 $ , the equilibrium constant $ K $ should be equal to one because:
We know that: $ \Delta {G^ \circ } = - RT\ln K $
 $ \ln K = 0 $
 $ K = 1 $
Therefore, option C is the correct answer.

Note :
 A small equilibrium constant or if the equilibrium constant is less than one, it means the chemical reaction favors the reactant and the reaction will proceed in the opposite direction. An equilibrium constant of one means the reactants and the products will be equal when the reaction reaches equilibrium.