Question

In a chemical reaction, substrate molecule A is broken down to form one molecule of product B and one molecule of product C. The equilibrium constant, K, for this reaction is 0.5. If we start with a mixture containing only substrate A at a concentration of 1 M, what will be the concentration of A when the reaction reaches equilibrium?

Answer 1

Concentration of A at equilibrium = 1 - 0.5 = 0.5 M

Step-by-step explanation:

`A \leftrightharpoons B + C`

Equilibrium constant = 0.5

Initial concentration of A = 1 M

`A \leftrightharpoons B + C`

Initial 1 0 0

At equi. 1-x x x

Equilibrium constant =
`([B][C])/([A])`

`0.5 = (x * x)/(1-x) \\0.5(1-x) = x^2\\0.5 -0.5x = x^2\\x^2+0.5x - 0.5 = 0`

on solving,

x = 0.5 M

Concentration of A at equilibrium = 1 - 0.5 = 0.5 M