Question

Bromine chloride, BrCl, decomposes to form chlorine and bromine. At a certain temperature the equilibrium constant for the reaction is 11.1 and the equilibrium mixture contains 4.00 mol Cl 2. How many moles of Br2 and BrCl are present in the equilibrium mixture?

Answer 1

Balanced equation of the reaction

2 moles of BrCl decomposes to give 1 mole of Br₂ and 1 mole of Cl₂

equilibrium mixture contains 4.00 mol Cl₂

                                                     2BrCl Br₂ + Cl₂

Let initial concentration (moles)         2x           0        0

At equilibrium  (moles)                  2x-4           4        4

Equuilibrium constant K = 11.1

K = [Br₂][Cl₂] /[BrCl]²

11.1 = 4 x 4/ (2x-4)² 3.33 =4 / (2x-4) 3.33 x (2x-4) =4 6.66x - 13.32 = 4

6.66 x =17.32 x = 17.32/6.66 = 2.6

Equilibrium concentration of BrCl= 2x-4=2x2.6 -4 =5.2-4= 1.2 moles

   Equilibrium concentration of Br₂ = 4 moles