An evacuated reaction vessel is filled with 3.60 atm of NOCl. When the system reaches equilibrium according to the reaction below, there are 0.160 atm of NOCl. What is Kp for this reaction? (27)

Question

2 NO (g) + Cl₂ (g) ⇌ 2 NOCl (g)

Answer 1

2 NO (g) + Cl₂ (g) ⇌ 2 NOCl (g)

.....................................3.60..........I

+2x.............+x............-2x..............C

..2x..............x...............0.16.........E

3.60 - 2x = 0.16

x = 1.72

Pressures at equilibrium:

NO = 2 x 1.72 = 3.44 atm

Cl₂ = 1.72 atm

NOCl = 0.16 atm

Kp = (NOCl)² / (NO)²(Cl₂) = (0.16)² / (3.44)²(1.72)

Kp = 1.26x10^-3