Asample of pure no2 gas decomposes at 1000 k                                 2no2 (g) ↔ 2 no (g) + o2 (g)   the constant kp is 158. an analysis shows that the partial pressure of o2 is 0.25 atmospheres at equilibrium. determine the pressure of no and no2.

- Equilibrium partial pressure of NO is 0.50 atm and equilibrium partial pressure of = 0.02 atm.

Solution:- Let's say the initial pressure of is p. We would make the ICE table for the given equation and consider the change in pressure as X.

I P 0 0

C -2X +2X +X

E (P-2X) 2X X

From given information, equilibrium partial pressure of oxygen is 0.25 atm and from ICE table it is X.

So, X = 0.25

equilibrium partial pressure of NO = 2(0.25 atm) = 0.50 atm

and equilibrium partial pressure of nitrogen dioxide = P-0.50

For the equation we have, the Kc expression would be written as:

Let's plug in the values in this expression:

This could also be written as:

On taking square root to both sides:

(P-0.50) = 0.0199

add 0.50 to both sides:

P = 0.0199 + 0.50

P = 0.5199 and it's rounded off to 0.52

Now, we could calculate the equilibrium partial pressure of nitrogen dioxide as:

equilibrium partial pressure of nitrogen dioxide = P-0.50

equilibrium partial pressure of nitrogen dioxide = 0.52-0.50 = 0.02 atm

So, equilibrium partial pressure of = 0.02 atm

equilibrium partial pressure of NO = 0.50 atm and