Question Detail
Question
Sulphuric acid vapour dissociates when heated according to the equation H₂SO₄(g) ⇌ H₂O(g) + SO₃(g). The equilibrium constant, Kp, for this reaction, at 400 K, is 2.06 atm. Calculate the equilibrium constant, Kc, at this temperature.
Correct Answer
Option B is the correct answer.
Detailed Explanation
Kp = Kc (RT)^(Δn). Δn = moles gaseous products - moles gaseous reactants = 2 - 1 = 1. Kc = Kp / (RT) = 2.06 atm / (0.0821 L·atm·mol⁻¹·K⁻¹ × 400 K) = 2.06 / 32.84 = 0.0627 mol dm⁻³.
Hint
Use the relation Kp = Kc (RT)^(Δn). Remember R = 0.0821 L·atm·mol⁻¹·K⁻¹.