A student is studying the equilibrium CO(g) + 2 H₂(g) ⇌ CH₃OH(g) at 500 K
CHEMISTRY · Multi-part · A Level · Chemistry · Chemical equilibria (Le Chatelier’s principle and Kc) · Chemical equilibria (Le Chatelier’s principle and Kc)
Problem
A student is studying the equilibrium
CO(g) + 2 H₂(g) ⇌ CH₃OH(g) Kc=15 at 500 K.
The student sketches a particulate model representing the equilibrium mixture in a closed container of fixed volume. The diagram (described verbally) contains 6 CO particles, 12 H₂ particles, and 4 CH₃OH particles. No other species are present.
Answer the following questions about the student’s representation.
(a) Describe the mathematical expression for Kc for this reaction and explain how particle counts in a valid particulate diagram relate to the terms in that expression.
(b) Using only the particle numbers provided, calculate the value of the reaction quotient Qc represented by the student’s diagram.
(c) Compare the Qc value you obtained in part (b) with the equilibrium constant Kc. Explain clearly whether the student’s diagram is consistent with a system at equilibrium at 500 K.
(d) If the diagram is not consistent with equilibrium, identify which species’ particle count(s) must increase or decrease to reach equilibrium and justify your reasoning in terms of the reaction stoichiometry.
(e) In one or two sentences, describe the most important conceptual feature that any correct particulate diagram must exhibit when representing a chemical equilibrium.