Question

Which of the following reactions lies to the right, favoring the formation of products, and which lies to the left, favoring formation of reactants? (a) \(2 \mathrm{NO}(g)+\mathrm{O}_{2}(g) \rightleftharpoons 2 \mathrm{NO}_{2}(g) ; K_{p}=5.0 \times 10^{12}\) (b) \(2 \mathrm{HBr}(g) \rightleftharpoons \mathrm{H}_{2}(g)+\mathrm{Br}_{2}(g) ; K_{c}=5.8 \times 10^{-18}\)

Short answer

Reaction (a) lies to the right, favoring the formation of products, since the equilibrium constant Kp = 5.0 × 10^12 is much greater than 1. On the other hand, reaction (b) lies to the left, favoring the formation of reactants, since the equilibrium constant Kc = 5.8 × 10^(-18) is much less than 1.

Step-by-step solution

Reaction (a)

For this reaction, we have the equilibrium constant Kp = 5.0 × 10^12. Since Kp is much greater than 1 (Kp >> 1), we can conclude that this reaction favors the formation of products. Therefore, reaction (a) lies to the right.

Reaction (b)

For this reaction, we have the equilibrium constant Kc = 5.8 × 10^(-18). Since Kc is much less than 1 (Kc << 1), we can conclude that this reaction favors the formation of reactants. Therefore, reaction (b) lies to the left.