Which of the following reactions lies to the right, favoring the formation of products, and which lies to the left, favoring the formation of reactants?
(a) 2 NO(g) + O₂(g) ⇌ 2 NO₂(g) Kp = 5.0 × 10¹²
(b) 2 HBr(g) ⇌ H₂(g) + Br₂(g) K_c = 5.8×10⁻¹⁸

Verified step by step guidance

1. Identify the given equilibrium constant (Kc) for the reaction: Kc = 5.8×10^(-18).
2. Recognize that a very small Kc value (much less than 1) indicates that the equilibrium heavily favors the reactants.
3. Understand that the reaction 2 HBr(g) ⇌ H2(g) + Br2(g) with such a small Kc means that at equilibrium, the concentrations of H2(g) and Br2(g) are very low compared to the concentration of HBr(g).
4. Conclude that the reaction lies to the left, favoring the formation of reactants over the formation of products.
5. This analysis is based on the equilibrium constant's magnitude and its relation to the position of equilibrium in a chemical reaction.

Key Concepts

Chemical Equilibrium

Chemical equilibrium occurs when the rates of the forward and reverse reactions are equal, resulting in constant concentrations of reactants and products. The position of equilibrium can shift to favor either reactants or products based on conditions such as concentration, temperature, and pressure.

Equilibrium Constant (Kc)

The equilibrium constant (Kc) quantifies the ratio of the concentrations of products to reactants at equilibrium for a given reaction at a specific temperature. A large Kc value (greater than 1) indicates that products are favored, while a small Kc value (less than 1) suggests that reactants are favored.

Le Chatelier's Principle

Le Chatelier's Principle states that if a dynamic equilibrium is disturbed by changing the conditions, the system will adjust to counteract the change and restore a new equilibrium. This principle helps predict how changes in concentration, temperature, or pressure will affect the position of equilibrium.