Question

A reaction mixture at 175 k initially contains 522 torr of no and 421 torr of o2. at equilibrium, the total pressure in the reaction mixture is 748 torr. calculate kp at this temperature.

Answer 1

The chemical equation would be:

2NO(g) + O2(g) --> 2NO2 (g) 

At equilibrium state, the partial pressure of the gases would be as follows : 

NO = 522 - 2x 

O2 = 421 - x 

NO2 = 2x 
- - - - - - - - - - - - -
943 - x = 748 

x = 195

Calculating for Kp,

Kp = (NO2)^2/ ((NO)^2 * (O2)) 

Kp = (2 * 195)^2/ ((522 - 2 * 195)^2 * (421 - 195)) 

Kp = 0.0386