Consider the following reactions and their respective equilibrium constants.

Question

Consider the following reactions and their respective equilibrium constants. 

NO(g)+1/2Br2​(g)⇌NOBr(g) Kp​ = 5.3

2NO(g)⇌N2​(g)+O2​(g) Kp​ = 2.1×10³⁰​ 

Use these reactions to calculate the equilibrium constant for N2​(g)+O2​(g)+Br2​(g)⇌2NOBr(g) 

Answer 1

N₂​(g) + O₂​(g) ⇌ 2NO(g) K_p​ = 1/(2.1×10³⁰)

2NO(g) + Br₂​(g) ⇌ 2NOBr(g) K_p​ = (5.3)²

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N₂​(g) + O₂​(g) + Br₂​(g) ⇌ 2NOBr(g) K_p​ = (5.3)² /(2.1×10³⁰) = 1.3 × 10^–29

Explanation

We alter the equations whose equilibrium constants are known so we can add them together to obtain the equation whose equilibrium constant we are trying to calculate.

2NO(g) ⇌ N₂​(g) + O₂​(g) K_p​ = 2.1×10³⁰​ needed to be reversed in direction

The equilibrium constant of the reversed reaction is the reciprocal of the original equilibrium constant.

NO(g) +1/2Br₂​(g) ⇌ NOBr(g) Kp​ = 5.3

Each of the coefficients of this reaction had to be doubled.

The equilibrium constant of the resulting reaction is the square of the original equilibrium constant.