Calculate the value of K under the reaction conditions.

Question

For the reaction in a sealed container at a constant temperature,

2NO(g)+Br_2​(g) <=> 2NOBr(g)

the initial concentrations are 4.25 M NO, 8.10 M Br₂, and no NOBr. At equilibrium, [NOBr] = 1.78 M.

Calculate the value of K under the reaction conditions.

Answer 1

2NO(g) + Br2(g) <===> 2NOBr(g)

4.25..........8.10...................0............Initial

-2x..........-x.......................+2x..........Change

4.25-2x...8.10-x.................2x...........Equilibrium

Substituting 1.78 for [NOBr] we can solve for x:

2x = 1.78 M

x = 0.89

Equilibrium concentrations are as follows:

[NO] = 4.25 - 1.78 = 2.47 M

[Br2] = 8.10 - 0.89 = 7.21 M

[NOBr] = 1.78 M

Writing the equilibrium expression, we have...

K = [NOBr]² / [NO]²[Br₂] = (1.78)² / (2.47)²(7.21)

K = 3.17 / 43.99

K = 0.0721