Question

The value of K_P for the reaction of nitrogen and oxygen to make nitrogen monoxide is 0.000376. The initial partial pressure of nitrogen monoxide is 1.283 atm with no nitrogen or oxygen. What is the equilibrium partial pressure (in atm) of oxygen?

Answer 1

Reaction: N2 + O2 <----> 2NO

Initial : 0 0 1.283

Change: +x +x - 2x

Equilibrium: x x 1.283 - 2x

Then using the formula as follows

Kp = [NO]2/[O2][N2] = (1.283 - 2x)2/x2

0.000376 = (1.283 - 2x)*(1.283 - 2x)/(x*x)

x = 0.63534, 0.64778

Then 2x = 1.27, 1.29(>1.283 => rejected

So, x = 0.63534 is correct.

Therefore, equilibrium partial pressure of oxygen is 0.63534 atm.

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