Question

Which of the following factors will not disturb the equilibrium state of the reaction? $H_2\left(g\right)+I_2\left(g\right)+heat\rightleftharpoons 2HI\left(g\right)$

• A. Change in temperature
• B. Addition of catalyst
• C. Addition of $H_2$
• D. Addition of $I_2$

Answer 1

The correct option is B Addition of catalyst

$\bullet$ As per Le- Chatelier's principle,
Since this reaction is an endothermic reaction, change in temperature will affect the equilibrium state. An increase in temperature will favor the products while a decrease in temperature will favor the reactant side.

$\bullet$ Effect of change in concentration of reactant and/or product:
In an equilibrium increasing the concentrations of reactants results in shifting the equilibrium in favour of products. So, addition of $H_2$ or $I_2$will shift the equilibrium toward the right.

$\bullet$ Catalyst is a substance which can change the speed of a chemical reaction without itself getting consumed. The function of the catalyst is to simply reach the point of equilibrium in less/more time than usual.
So a catalyst can only have its effect on the rate of the reaction and not on the equilibrium constant of the reaction.