A chemical plant synthesizes methanol by the gas-phase equilibrium reaction CO(g) + 2…
CHEMISTRY · Multi-part · A Level · Chemistry · Chemical equilibria (Le Chatelier’s principle and Kc) · Chemical equilibria (Le Chatelier’s principle and Kc)
Problem
A chemical plant synthesizes methanol by the gas-phase equilibrium reaction
CO(g) + 2 H₂(g) ⇌ CH₃OH(g) ΔH° = –91 kJ mol⁻¹
The reaction is carried out in a closed, high-pressure vessel that allows independent adjustment of temperature, total pressure, and continuous removal of liquid methanol as it condenses downstream.
Answer the following, referring explicitly to the information provided in the stimulus.
(a) When the reaction mixture at equilibrium is suddenly heated by 50 K while volume is held constant, qualitatively predict the direction in which the equilibrium position will shift. Explain your reasoning.
(b) The original equilibrium mixture (before heating) is instead compressed by reducing the vessel volume to one-half its initial value at constant temperature. Predict the direction of the equilibrium shift and justify your answer.
(c) Suppose liquid methanol is continuously removed from the system as it forms, while temperature and pressure are kept constant. Explain how this operation affects the position of equilibrium and the equilibrium constant.
(d) An inert gas is injected into the equilibrium mixture while the vessel volume is simultaneously increased so that total pressure remains constant. Predict whether the equilibrium position will shift and justify your answer.
(e) Using your answers to parts (a)–(d), recommend a combination of temperature control and pressure control strategies that would maximize the equilibrium molar yield of methanol in a single pass. Provide a concise justification referencing enthalpy change and reaction stoichiometry.