Answer:
Kp = 4.5 x 10⁻⁹
Explanation:
from equilibrium of gas phase rxns, Kp = Kc(R·T)^-Δn
2NH₃(g) ⇄ 3H₂(g) + N₂(g)
2Vm 3Vm 1Vm
Δn = ∑Vm(products) - ∑Vm(reactants) = (3Vm + 1Vm) - 2Vm = 2Vm = +2
Kc = Kb = [H₂]³[N₂]/[NH₃]² = 1.8 x 10⁻⁵M²
R = 0.08206 L·atm/mol·K
T = 500°C = (500 + 273)K = 773K
Kp = Kb(R·T)^-Δn = 1.8 x 10⁻⁵M²[(0.08206L·atm/mol·K)(773K)]⁻⁽⁺²⁾
= (1.8 x 10⁻⁵mol²/L²)(63.43atm/mol)⁻²
= 4.5 x 10⁻⁹atm
Hope this helps. :-)
