The equilibrium constants (expressed in atm) for the chemical reaction N₂(g) + O₂(g) 2NO(g) are K_P = 1.1 × 10^-3 and 3.6 × 10^-3 at 2200 K and 2500 K, respectively.
Which statement is true?

Question

The equilibrium constants (expressed in atm) for the chemical reaction N₂(g) + O₂(g) 2NO(g) are K_P = 1.1 × 10^-3 and 3.6 × 10^-3 at 2200 K and 2500 K, respectively. Which statement is true?

Quizplus · Accepted Answer

According to Le Chatelier's principle, an increase in temperature favors the endothermic reaction in order to absorb the excess heat. Therefore, the equilibrium will shift to the right at higher temperature, resulting in a higher concentration of NO(g). Thus, the partial pressure of NO(g) will be higher at 2500 K than at 2200 K, and statement B is true. The equilibrium constant expression in terms of partial pressures, Kp, can be related to the equilibrium constant expression in terms of concentrations, Kc, by the following equation: Kp = Kc(RT)^(Δn), where Δn is the difference in the number of moles of gas between products and reactants. Since Δn = 2 - 2 = 0 for this reaction, K_p = K_c(RT)^(0) = K_c, and statement C is false. We cannot determine if the reaction is exothermic or endothermic based on the given information, and statement A is false. The total pressure at equilibrium depends on the initial pressures of N₂(g) and O₂(g), and we cannot determine if they are the same at 2200 K and 2500 K, so statement D is uncertain. Higher total pressure favors the side with fewer moles of gas, which is the left side in this case, so statement E is false.

The Equilibrium Constants (Expressed in Atm) for the Chemical Reaction