At 298 K the equilibrium constant for the reaction is

CHEMISTRY · Single correct · A Level · Chemistry · Chemical equilibria (Le Chatelier’s principle and Kc) · Chemical equilibria (Le Chatelier’s principle and Kc)

Problem

At 298 K the equilibrium constant for the reaction 2 NO2(g)⇋N2O4(g)\mathrm{2\,NO_2(g)\leftrightharpoons N_2O_4(g)} is Kc=2.1×10−3K_c = 2.1 \times 10^{-3}. What is KcK_c for the reaction written in the opposite direction, N2O4(g)⇋2 NO2(g)\mathrm{N_2O_4(g)\leftrightharpoons 2\,NO_2(g)}, and what does this imply about the relative equilibrium concentrations of NO2\mathrm{NO_2} and N2O4\mathrm{N_2O_4}? (a) Kc=2.1×10−3;K_c = 2.1 \times 10^{-3}; the mixture is predominantly NO2\mathrm{NO_2}. (b) Kc=2.2×101;K_c = 2.2 \times 10^{1}; the mixture is predominantly NO2\mathrm{NO_2}. (c) Kc=4.8×102;K_c = 4.8 \times 10^{2}; the mixture is predominantly NO2\mathrm{NO_2}. (d) Kc=4.8×102;K_c = 4.8 \times 10^{2}; the mixture is predominantly N2O4\mathrm{N_2O_4}.

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