Question

What happens when an inert gas is added to an equilibrium keeping volume unchanged ?

• A. More product will form
• B. Less product will form
• C. More reactant will form
• D. Equilibrium will remain unchanged

Answer 1

The Correct Option is D

In this question, we need to determine what happens to a chemical equilibrium when an inert gas is added, keeping the volume unchanged. Let's analyze this situation using the principles of chemical equilibrium. 

An inert gas, such as helium or neon, does not react with either the reactants or the products in the equilibrium reaction. Therefore, its introduction into the system will not participate in the chemical reaction.

According to Le Chatelier's Principle, a system at equilibrium will adjust itself to counteract any changes imposed on it. However, when an inert gas is added and the volume of the system remains constant, the total pressure of the system may increase due to the extra gas, but the partial pressures of the reactants and products—the factors that determine the position of equilibrium, according to the equilibrium constant expression—remain unchanged. This is because:

• The equilibrium constant, \(K_p\), is a function of the products of the partial pressures of the gases involved in the equilibrium equation at a given temperature. It does not include the inert gases.
• The partial pressures of the reactants and products are unaffected because the total volume is unchanged, and the inert gas does not react.

As a result, the equilibrium position and the equilibrium constant remain unchanged by the addition of an inert gas if the volume is constant.

Hence, based on the explanation above, the correct answer is:

Correct Answer

Equilibrium will remain unchanged

Understanding how external changes affect chemical equilibria helps in predicting the direction of the shift in equilibrium, if any, thereby aiding decision-making in chemical processes.