CHEMISTRY · Single correct · A Level · Chemistry · Chemical equilibria (Le Chatelier’s principle and Kc) · Chemical equilibria (Le Chatelier’s principle and Kc)
Problem
For the gas-phase reaction A2(g)⇌2A(g) at 750 K, an equilibrium mixture is contained in a rigid vessel. An inert gas is suddenly injected, doubling the total pressure while the temperature remains constant. Which statement about the equilibrium constant for the reaction is correct?
(a) Kc doubles because the partial pressure (and therefore concentration) of every species doubles.
(b) Kc is unchanged because it depends only on temperature.
(c) Kc remains unchanged, but Kp doubles since the total pressure doubles.
(d) Kc is halved because the system shifts toward the side with fewer gas molecules when pressure increases.