Ammonium carbamate (NH2COONH4) is found in the blood and urine of mammals.

Question

Ammonium carbamate (NH₂COONH₄) is found in the blood and urine of mammals. At a temperature of 340 K, K_c = 0.568 for the following equilibrium:

NH₂COONH₄(s) <=> 2 NH₃(g) + CO₂(g).

If 10.2 g of ammonium carbamate is introduced into a 0.500 L container, what is the total pressure inside the container at equilibrium?

Give your answer to 2 decimal places.

Correct Answer:

 43.69 ± 2%

Answer 1

NH₂COONH₄(s) <===> 2NH₃(g) + CO₂(g)

Since ammonium carbamate is a solid, it does not appear in the equilibrium expression. Thus, we have...

Kc = 0.568 = [NH₃]²[CO₂] = (2x)²(x) = 4x³

x³ = 0.142

x = 0.522

At equilibrium...

[NH₃] = 2x = 2*0.522 = 1.04

[CO₂] = x = 0.522

PV = nRT

P = nRT/V and n/V = concentration

P = concentration x RT

P_{total =} (1.04)(0.0821)(340) + (0.522)(0.0821)(340) = 29.14 + 14.57 = 43.71 atm (differs from answer given because of rounding)