Question

You're provided with a bottle labled [CoCl2.6H2O] = 0.051 M in 4.60 M HCl. You heat a small volume of the solution in a hot water bath to 50 ∘C. If you determine that [CoCl42-] = 0.031 M at 50 ∘C at equilibrium, what must be the equilibrium concentration of [Cl-] at 50 ∘C?

Answer 1

Answer : The concentration of
`Cl^-` at equilibrium is 4.54 M

Explanation :

The equilibrium reaction will be:

`[CoCl_2.6H_2O]+2Cl^-\rightleftharpoons [CoCl_4]^(2-)+6H_2O`

Initial 0.051 M 4.60 M 0

At eqm. (0.051-x) M (4.60-2x) M x

As we are given:

Concentration of
`[CoCl_4]^(2-)` at equilibrium = 0.031 M

That means,

x = 0.031 M

Concentration of
`Cl^-` at equilibrium = (4.60-2x) M = [4.60-2(0.031)] M = 4.54 M

Hence, the concentration of
`Cl^-` at equilibrium is 4.54 M