Question

The Kp for the reaction below is 1.49 × 108 at 100.0°C:

CO(g) + Cl2(g) → COCl2(g)

In an equilibrium mixture of the three gases, PCO = PCl2 = 2.22 × 10-4 atm. The partial pressure of the product, phosgene (COCl2), is ________ atm.

Answer 1

The rate constants, K, can be expressed in many different terms. In this case, Kp is the equilibrium constant expressed in terms of gas partial pressure. The formula for this is:
Kp = [P(product C) × P(product D)] / [P(reactant A) × P(reactant B)]
As there is only one product, we will use only its pressure in the numerator.
Kp = [P(COCl2)] / [P(CO) × P(Cl2)]
P(COCl2) = 1.49 × 10⁸ × 2.22 × 10⁻⁴ × 2.22 × 10⁻⁴
P(COCl2) = 7.34 atm