A closed vessel at contains only species A initially
CHEMISTRY · Multi-part · A Level · Chemistry · Chemical equilibria (Le Chatelier’s principle and Kc) · Chemical equilibria (Le Chatelier’s principle and Kc)
Problem
A closed vessel at 298K contains only species A initially. The elementary isomerization
A⇌B
is known to have a forward rate constant of 2.0×10−9s−1 at this temperature. After 24h, quantitative analysis shows no detectable concentration of B, and a student concludes that the system must already be at equilibrium.
(a) State the condition that must be satisfied for a chemical system to be at equilibrium in terms of the microscopic reaction rates.
(b) Using the numerical value of the forward rate constant, explain why the absence of observable B after 24h does not, by itself, demonstrate that equilibrium has been reached.
(c) Propose a specific experimental perturbation that would allow you to distinguish between a kinetically inhibited system and one that is truly at equilibrium. Predict the qualitative outcome of your test for each case and justify your reasoning.