Question

Write the equilibrium-constant expression for the reaction?

Answer 1

`K_c = [C]^2[D]`

Explanation:

The equilibrium expression for the equilibrium constant based on concentration, `K_c`, is essentially defined as the ratio of the concentrations of the products over the reactants, with everything raised to the power of their coefficient in the reaction.

So, if we had this reaction:

`A(aq) + 2B(aq) rightleftharpoons 3C(aq) + 4D(aq)`

The equilibrium expression would be:

`K_c = ([C]^3[D]^4)/([A][B]^2)`

But there’s one thing—in the equilibrium expression, pure solids and liquids are excluded and given a concentration of `1`.

This is mainly because the concentrations of solids and liquids cannot change.

So, if we had our given reaction:

`A(s) + 3B(l) rightleftharpoons 2C(aq) + D(aq)`

We wouldn’t include `A` or `B` in the equilibrium expression, since they’re pure solids and liquids.

As such, our equilibrium expression would be:

`K_c = [C]^2[D]`