A sample of carbon is placed in a rigid 1.50 L flask. Dinitrogen monoxide is added and the flask heated to 800C. When the system reached equilibrium the partial pressure of the carbon dioxide is found to be 0.030 atm and the partial pressure of the dinitrogen monoxide to be 1.48 atm. What is the value of the equilibrium constant, Kp for the system at 800C?

1 Answer
May 22, 2014

The value of KP is 4.9 × 10⁻⁵.

1. Write the balanced chemical equation for the equilibrium.

C(s) + 2N₂O(g) ⇌ CO₂(g) + 2N₂(g)

2. Write the KP expression.

KP=PCO2P2N2P2N2O

3 List the equilibrium concentrations.

PCO2 = 0.030 atm

PN2O = 1.48 atm

There was no N2 in the system at the beginning. All the N2 present must have come from the reaction.

According to the equation, the reaction forms twice as much N2 as CO2. Thus,

PN2=2PCO2 = 2 × 0.030 atm = 0.060 atm

4. Insert these values into the KP expression

KP=PCO2P2N2P2N2O=0.030×0.0602(1.48)2 = 4.9 × 10⁻⁵