Question

Ammonia and hydrochloric acid react to form ammonium chloride according to the equation: NH3(g) + HCl(g) ⇌ NH4Cl(s). If a student were to add 0.1 moles of NH4Cl to the mixture at equilibrium and the volume of the container is constant, what will be the new concentration of NH3(g) and HCl(g) in the mixture?

Answer 1

To solve this problem, we need to use the concept of equilibrium and the reaction quotient  Q . The reaction quotient is the ratio of the concentrations of the products to the reactants, raised to the power of their stoichiometric coefficients. For this reaction, the equilibrium constant  K  is given by:K = [NH4Cl] /  [NH3] * [HCl] Since the reaction is at equilibrium, Q = K. When 0.1 moles of NH4Cl are added, the reaction will no longer be at equilibrium, and the system will shift to re-establish equilibrium. Let's call the change in concentration of NH3 and HCl "x". At the new equilibrium, the concentrations will be:[NH3] = [NH3] - x[HCl] = [HCl] - x[NH4Cl] = [NH4Cl] + 0.1Now, we can write the new reaction quotient Q:Q =  [NH4Cl] + 0.1  /   [NH3] - x  *  [HCl] - x  Since the system will shift to re-establish equilibrium, Q will once again equal K:K =  [NH4Cl] + 0.1  /   [NH3] - x  *  [HCl] - x  Unfortunately, we cannot solve this equation without knowing the initial concentrations of NH3, HCl, and NH4Cl, as well as the value of K. If you provide these values, we can solve for the new concentrations of NH3 and HCl.