The water–gas shift reaction is important in industrial hydrogen production: H (g) +…
CHEMISTRY · Multi-part · A Level · Chemistry · Chemical equilibria (Le Chatelier’s principle and Kc) · Chemical equilibria (Le Chatelier’s principle and Kc)
Problem
The water–gas shift reaction is important in industrial hydrogen production:
H2(g) + CO2(g) ⇌ H2O(g) + CO(g) Kc=1.50 at 986 K
A rigid 2.00 L vessel is filled at 986 K with 0.400 mol H2(g), 0.200 mol CO2(g), 0.100 mol H2O(g), and 0.0500 mol CO(g).
(1) Determine the initial molar concentration of each species in the vessel.
(2) Calculate the reaction quotient Qc for the initial mixture.
(3) Compare Qc with Kc and predict the direction in which the reaction will shift as it moves toward equilibrium. Justify your conclusion.
(4) The forward direction of the reaction is exothermic. If the temperature of the system is suddenly increased while the volume remains constant, discuss qualitatively how the value of Kc will change and predict the initial direction of the shift (if any) immediately after the temperature increase. Explain your reasoning in terms of thermodynamics and the reaction quotient.