Flashcards · 7405 · A Level Topic 10

Equilibrium constant Kp for homogeneous systems (A Level) flashcards

8 cards on A Level Topic 10. Pick a subtopic or study them all.

Study mode needs JavaScript. Every card is listed below, so you can still cover the answers and test yourself.

All 8 cards

For a quick read-through or printing. Cover the right-hand side to test yourself.

Mole fraction: x(A) = moles of A ÷ total moles of gas in the mixture. No units; all mole fractions add up to 1.
Partial pressure: p(A) = x(A) × total pressure: the pressure gas A would exert if it alone filled the container. Partial pressures add up to the total pressure.
Kp expression for N₂(g) + 3H₂(g) ⇌ 2NH₃(g), with units in kPa: Kp = p(NH₃)² ÷ (p(N₂) × p(H₂)³). Units: kPa⁻².
Units of Kp for N₂O₄(g) ⇌ 2NO₂(g) with pressures in kPa: kPa (Δn = 2 − 1 = +1).
Effect of raising total pressure on Kp and on the position: Kp does not change at constant temperature. The position shifts to the side with fewer moles of gas.
Forward reaction endothermic, temperature raised: effect on Kp: The equilibrium shifts right, so Kp increases.
0.900 mol A, 0.300 mol B, 0.600 mol C at a total pressure of 180 kPa. Partial pressures?: Total 1.800 mol. p(A) = 0.500 × 180 = 90.0 kPa; p(B) = 30.0 kPa; p(C) = 60.0 kPa. They sum to 180 kPa.
Classic trap when finding the total moles of gas for mole fractions: Use equilibrium moles, not initial moles, and include products that started at zero.