Consider the reversible reaction carried out in a rigid 2.00-L vessel at constant…
CHEMISTRY · Multi-part · A Level · Chemistry · Chemical equilibria (Le Chatelier’s principle and Kc) · Chemical equilibria (Le Chatelier’s principle and Kc)
Problem
Consider the reversible reaction carried out in a rigid 2.00-L vessel at constant temperature:
A(g) ⇌ 2 B(g)
At 10.0 min after mixing the reactants, both the forward and reverse rates are measured to be 0.25 mol L⁻¹ s⁻¹. At that same instant the concentration of A is found to be 0.40 M, and the concentrations have remained unchanged for at least 2 min.
(a) Calculate the amount (in moles) of A converted to B each second at 10.0 min.
(b) Using the stoichiometry of the reaction, determine the corresponding number of moles of B formed and the number of moles of B that simultaneously react to re-form A each second.
(c) Explain why the concentrations of both A and B remain constant even though the numerical changes in moles of the two species are not the same.
(d) A student claims that because A and B are produced and consumed in different stoichiometric ratios, the rates of the two reactions cannot truly be equal. Evaluate this claim, citing quantitative evidence from parts (a) and (b).