Finding partial pressure at equilibrium?

Question

One method for producing hydrogen is to react coke (mostly solid carbon) with steam to make syngas, a mixture of CO and hydrogen

C(s) + H₂O(g) ⇌ CO(g) + H₂(g)     K_p = 0.45 at 900 K     ΔH = +131 kJ

What is the partial pressure of H₂ at equilibrium when 8.00 atm of H₂O(g) is heated with excess C(s) at 900 K?

P_H2 =  atm

Answer 1

C(s) + H₂O(g) ⇌ CO(g) + H₂(g)

0........8 atm..........0............0......initial

..........-x..............+x...........+x.....change

........8-x................x............x......equilibrium

Kp = 0.45 = (CO)(H₂)/(H₂O)

0.45 = (x)(x)/8-x

3.6 - 0.45x = x²

x² + 0.45x - 3.6 = 0

x = 1.69 atm = partial pressure of H₂