What is the total pressure in the container after equilibrium has been established?

Question

Ammonium carbamate, NH₄OCONH₂, decomposes to produce ammonia and carbon dioxide. At 25.05 °C the value K_p for this reaction is 0.00402 .

NH₄OCONH₂ reaction ---> 2NH₃ + CO₂

A large amount of solid ammonium carbamate is placed in a rigid container at 25.05 °C and allowed to come to equilibrium. What is the total pressure in the container after equilibrium has been established?

Answer 1

NH₄OCONH₂(s) <==> 2NH₃(g) + CO₂(g)

Let us write the Kp expression for this reaction, recalling that NH₄OCONH₂ is a solid and as such will not appear in the expression:

Kp = (NH₃)²(CO₂)

0.00402 = (2x)²(x) = 4x³

x = 0.100

Partial pressure NH3 = 2 x 0.100 = 0.200

Partial pressure CO2 = x = 0.100

Total pressure @ equilibrium = 0.200 + 0.100 = 0.300