At 700 K, sulfur dioxide and oxygen combine to form sulfur trioxide according to 2…
CHEMISTRY · Multi-part · A Level · Chemistry · Chemical equilibria (Le Chatelier’s principle and Kc) · Chemical equilibria (Le Chatelier’s principle and Kc)
Problem
At 700 K, sulfur dioxide and oxygen combine to form sulfur trioxide according to
2 SO2(g) + O2(g) ⇌ 2 SO3(g) Kc = 4.5 × 10^2.
A 5.00 L container at 700 K initially holds 0.50 mol SO2(g), 0.50 mol O2(g), and no SO3(g).
(a) Calculate the initial molar concentration of each species.
(b) Let x be the molarity of SO3(g) present at equilibrium. Write expressions for the equilibrium concentrations of all three gases in terms of x.
(c) Substitute these expressions into the equilibrium‐constant relation to obtain a single algebraic equation in x. Given the large numerical value of Kc, apply an appropriate simplifying assumption to avoid solving a full quadratic, and justify the validity of that assumption numerically.
(d) Determine the equilibrium molar concentration of each species, reporting values to the correct number of significant figures.