Question

The reaction quotient (Q) for the reaction \(N_2(g) + 3H_2(g)⇋2NH_3(g)\) is given by \(Q =\frac { [NH_3]^2}{[N_2][H_2]^3}\). The reaction will proceed from right to left if: (where K_C is the equilibrium constant)

• A. Q=KC
• B. Q
• C. Q>KC
• D. Q=0

Answer 1

The Correct Option is C

The reaction quotient \(Q\) is used to determine the direction in which a chemical reaction will proceed to reach equilibrium. It is given by the expression:

\(Q = \frac { [NH_3]^2}{[N_2][H_2]^3}\) 

Here, \(Q\) is compared with the equilibrium constant \(K_C\) to predict the reaction's direction:

If \(Q = K_C\), the system is at equilibrium, and no net change occurs.

If \(Q < K_C\), the reaction will proceed from left to right, favoring the formation of products to reach equilibrium.

If \(Q > K_C\), the reaction will proceed from right to left, favoring the formation of reactants to reach equilibrium.

Given the options and based on the aforementioned reasoning:

• Option "Q = K_C": The system is at equilibrium, not favoring any direction.
• Option "Q < K_C": The reaction shifts from reactants to products, i.e., left to right. Hence, incorrect.
• Option "Q > K_C": The reaction shifts from products to reactants, i.e., right to left. This is the correct choice.
• Option "Q = 0": This situation is unlike in practical scenarios as all products must have non-zero concentrations.

Consequently, the correct answer is the reaction will proceed from right to left if \(Q > K_C\).