Nitrogen monoxide and oxygen react to form nitrogen dioxide according to 2 NO(g) +…
CHEMISTRY · Multi-part · A Level · Chemistry · Chemical equilibria (Le Chatelier’s principle and Kc) · Chemical equilibria (Le Chatelier’s principle and Kc)
Problem
Nitrogen monoxide and oxygen react to form nitrogen dioxide according to
2 NO(g) + O₂(g) ⇌ 2 NO₂(g)
A 10.0 L rigid container at 450 K initially contains 0.300 mol of NO(g) and 0.100 mol of O₂(g). After the mixture reaches equilibrium, analysis shows that 0.120 mol of NO₂(g) is present.
Assume ideal-gas behavior for all gases.
(a) Calculate the number of moles of NO(g) and O₂(g) that remain in the container at equilibrium.
(b) Determine the equilibrium molar concentrations of NO, O₂, and NO₂.
(c) Compute the numerical value of the equilibrium constant Kc at 450 K.
(d) The volume of the vessel is now reduced to 5.00 L while the temperature remains at 450 K. Predict qualitatively how the partial pressures of each species will change immediately after compression and state which direction (toward reactants or toward products) the system will shift to reach a new equilibrium. Justify your answer in terms of Le Châtelier’s principle and the reaction quotient.