What is the pressure of BrCl in an equilibrium mixture of Cl2, Br2, and BrCl if the pressure of Cl2 in the mixture is 0.115 atm and the pressure of Br2 in the mixture is 0.450 atm?

Question

What is the pressure of BrCl in an equilibrium mixture of Cl₂, Br₂, and BrCl if the pressure of Cl₂ in the mixture is 0.115 atm and the pressure of Br₂ in the mixture is 0.450 atm?

Kc=4.7*10^-2

Answer 1

Your question does not state whether BrCl is decomposing to form Br₂ and Cl₂ OR Br₂ and Cl₂ are combining to form BrCl as this can affect the final answer. I will assume that BrCl is decomposing and the balanced chemical reaction is:

2 BrCl ⇔ Br₂ + Cl₂

K_p = K_c (RT)^Δn

where Δn = n_products - n_reactants = (1 + 1) - 2 = 2 - 2 = 0

since Δn = 0, then (RT)^Δn = (RT)⁰ = 1, and therefore, K_p = K_c = 4.7 x 10^-2.

K_p = (p_Br2) (p_Cl2) / (p_BrCl)²

(p_BrCl)² = (p_Br2) (p_Cl2) / K_p

(p_BrCl)² = (0.450 x 0.115) / 4.7 x 10^-2

(p_BrCl)² = 1.10

p_BrCl = √1.10 = 1.05 atm**

**NOTE! This answer is presuming the reaction is written as above.