Question

A mixture containing N₂O₄, N₂O, and O₂, all at an initial partial pressure of 4.60 atm, is allowed to achieve equilibrium according to the equation below. At equilibrium, the partial pressure of O₂ is observed to have decreased by 0.28 atm. Determine K_p for this chemical equilibrium. Report your answer to 3 significant figures in scientific notation.


2N₂O₄(g) ⇌ 2N₂O(g) + 3O₂(g)

Answer 1

Answer – We are given, P N₂O₄ = 4.60 atm , P N₂O =4.60 atm and

P O₂ = 4.60 atm , at equilibrium O₂ = 0.28 atm

      2N₂O₄(g) <----> 2N₂O(g) + 3O₂(g)

I   4.60                     4.60         4.60

C -2x                       +2x         +3x

E 4.60-2x                 4.60+2x     0.28

We know

At equilibrium,

P O₂ = 4.60+3x = 0.28

So, 3x = 0.28+4.60

So, x = -1.44

At equilibrium, P N₂O₄(g) = 4.60-2x

                                            = 4.60-2*-1.44

                                            = 7.48 atm

At equilibrium, P N₂O(g) = 4.60+2x

                                               = 4.60+2*-1.44

                                               = 1.72 atm

So, Kp = P (N₂O(g) )² * P(O₂(g))³ / P (N₂O₄(g))²

            = (1.72)² * (0.28)³ / (7.48)²

            = 0.00116