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# Bromine Monochloride, Brcl Decomposes into Bromine and Chlorine and Reaches the Equilibrium: What is Its Molar Concentration in the Mixture at Equilibrium? - CBSE (Science) Class 11 - Chemistry

ConceptApplications of Equilibrium Constants Calculating Equilibrium Concentrations

#### Question

Bromine monochloride, BrCl decomposes into bromine and chlorine and reaches the equilibrium:

2BrCl (g) ⇌ Br2 (g) + Cl2 (g)

for which Kc= 32 at 500 K. If initially pure BrCl is present at a concentration of 3.3 × 10–3 molL–1, what is its molar concentration in the mixture at equilibrium?

#### Solution

Let the amount of bromine and chlorine formed at equilibrium be x. The given reaction is:

2BrCl (g) ⇌ Br2 (g) + Cl2 (g)

Initial mole/litre                       0.0033          0           0

Moles/litre at eqm point          0.0033 - x    x/2         x/2

Applying Law of chemical equilibrium, K_C = ([Br_2][Cl_2])/[BrCl]^2  or 32 = ((x/2)xx(x/2))/(0.0033 - x)^2

On taking the square root, 5.656 = "x/2"/(0.0033 - x)

x/(0.0033- x) = 11.31 or 12.31x = 0.037 ; x = 0.037/12.31 = 0.003

∴Molar concentration of BrCl at equilibrium point  = 0.0033 - 0.003

= 0.003 mol L^(-1) = 3 xx 10^(-4) mol L^(-1)

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#### APPEARS IN

Solution Bromine Monochloride, Brcl Decomposes into Bromine and Chlorine and Reaches the Equilibrium: What is Its Molar Concentration in the Mixture at Equilibrium? Concept: Applications of Equilibrium Constants - Calculating Equilibrium Concentrations.
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