Chapter 7

Q. 7.10

Le Châtelier’s Principle and Equilibrium Mixtures
Nitrogen reacts with oxygen to give NO:

N_2(g) + O_2(g) \rightleftarrows  2 NO(g)    ΔH = +43 kcal/mol (+180 kJ/mol)

Explain the effects of the following changes on reactant and product concentrations:
(a) Increasing temperature                          (b) Increasing the concentration of NO
(c) Adding a catalyst


Verified Solution

(a) The reaction is endothermic (positive ΔH), so increasing the temperature favors the forward reaction. The concentration of NO will be higher at equilibrium.
(b) Increasing the concentration of NO, a product, favors the reverse reaction. At equilibrium, the concentrations of both N_2 and O_2, as well as that of NO, will be higher.
(c) A catalyst accelerates the rate at which equilibrium is reached, but the concentrations at equilibrium do not change.