Chemistry Equilibrium Question

Question

For the reaction N₂O₄(g)  2NO₂(g) , K_p = 0.25 at a certain temperature. Calculate the equilibrium pressures of NO₂(g) and N₂O₄(g) if the initial pressure(s) of the components when placed in an otherwise empty container are as follows:

Initial P_NO2 = 0.0 atm

Initial P_N2O4 = 0.040 atm

Equilibrium P_NO2 = ? atm

Equilibrium P_N2O4 = ? atm

Answer 1

I've done several of these before, so I'll just set it up and you should be able to complete it.

N₂O₄(g) <==>  2NO₂(g)

0.040................0...........Initial

-x..................+2x...........Change

0.040-x..........2x...........Equilibrium

Kp = 0.25 = (NO2)² / (N2O4) = (2x)² / (0.040-x)

0.25 = 4x² / 0.040 - x

Solve for x and P_NO2 will be 2x and P_N2O4 will be 0.040 - x