Sulfur trioxide decomposes according to
2 SO₃(g) ⇌ 2 SO₂(g) + O₂(g) ΔH° = +198 kJ
At 800 K the equilibrium partial pressures in a rigid container are
P(SO₃) = 0.80 atm, P(SO₂) = 0.10 atm, P(O₂) = 0.05 atm.
The equilibrium constants are Kₚ(800 K) = 1.2 × 10⁻² and Kₚ(900 K) = 4.8 × 10⁻².
The temperature is rapidly increased to 900 K while the volume of the container is doubled instantaneously. No reaction occurs during the brief interval of these changes.
(a) Calculate the numerical value of Q immediately after the temperature increase and volume expansion, using the new partial pressures that exist at that instant.
(b) Compare the value of Q obtained in part (a) with Kₚ(900 K). Predict the direction in which the system will shift to re-establish equilibrium at 900 K and justify your answer.
(c) Will the equilibrium partial pressure of O₂ at 900 K be greater than, less than, or equal to 0.025 atm (its value immediately after the volume change)? Provide a detailed explanation citing both ΔH° and the relative magnitudes of Q and Kₚ.