Question

In a gaseous reaction a + b ⇄ c + 2d, 3 mol of inert gas is introduced into the vessel at constant pressure. What will be its effect on equilibrium?

Answer 1

When an inert gas is added to the system in equilibrium at constant pressure, then the total volume will increase. Hence, the number of moles per unit volume of various reactants and products will decrease.

Hence, the equilibrium will shift towards the direction in which there is increase in number of moles of gases.

Consider the reaction in equilibrium:

            $a\quad +\quad b\quad \rightleftarrows \quad c\quad +\quad 2d$

The addition of 3 moles an inert gas at constant pressure to the above reaction will shift the equilibrium towards the forward direction because the number of moles of products is more than the number of moles of the reactants.

Answer 2

Answer:

Add an inert gas (one that is not involved in the reaction) to the constant-volume reaction mixture: This will increase the total pressure of the system, but will have no effect on the equilibrium condition. That is, there will be no effect on the concentrations or the partial pressures of reactants or products.