At 298 K, a sealed 1.00 L reaction vessel contains the gases CO(g), H2O(g), CO2(g),…
CHEMISTRY · Multi-part · A Level · Chemistry · Chemical equilibria (Le Chatelier’s principle and Kc) · Chemical equilibria (Le Chatelier’s principle and Kc)
Problem
At 298 K, a sealed 1.00 L reaction vessel contains the gases CO(g), H2O(g), CO2(g), and H2(g) involved in the water–gas shift equilibrium:
CO(g) + H2O(g) ⇌ CO2(g) + H2(g) Kc = 1.56.
The initial molar concentrations are [CO] = 0.10 M, [H2O] = 0.050 M, [CO2] = 0.020 M, and [H2] = 0.010 M.
(a) Calculate the numerical value of the reaction quotient Q for the initial mixture and state whether the system will shift toward reactants or toward products to reach equilibrium.
(b) Qualitatively describe how the concentration of each species will change as the system moves toward equilibrium, providing a brief explanation that refers to your answer in part (a).
(c) Without performing any numerical equilibrium calculation, outline a symbolic representation for the equilibrium concentrations of all four species by introducing a single algebraic symbol to denote the magnitude of change. Clearly indicate the sign of the change for each species and relate it to the stoichiometric coefficients in the balanced equation.