A solution containing CaCl2 is mixed with a solution of Li2SO4 to form a solution that is 2.1 × 10-5 M in calcium ion and 4.75 × 10-5 M in sulfate ion. What will happen once these solutions are mixed? The Ksp for CaSO4 is 2.4 x 10-5.

Respuesta :

Answer : The precipitate will not be formed when these solutions are mixed.

Explanation :

The chemical equation for the reaction of calcium chloride and lithium sulfate follows:

[tex]CaCl_2(aq)+Li_2SO_4(aq)\rightarrow 2LiCl(aq)+CaSO_4(s)[/tex]

We are given:

Concentration of calcium ion = [tex]2.1\times 10^{-5}M[/tex]

Concentration of sulfate ion = [tex]4.75\times 10^{-5}M[/tex]

[tex]K_{sp}=2.4\times 10^{-5}[/tex]

The salt produced is calcium sulfate.

The equation follows:

[tex]CaSO_4(s)\rightleftharpoons Ca^{2+}(aq)+SO_4^{2-}(aq)[/tex]

The expression of [tex]Q_{sp}[/tex] (ionic product) for above equation follows:

[tex]Q_{sp}=[Ca^{2+}]\times [SO_4^{2-}][/tex]

Putting values of the concentrations in above expression, we get:

[tex]Q_{sp}=(2.1\times 10^{-5})\times (4.75\times 10^{-5})\\\\Q_{sp}=9.9\times 10^{-10}[/tex]

There are 3 conditions:

  • When [tex]K_{sp}>Q_{sp}[/tex]; the reaction is product favored.  (No precipitation)
  • When [tex]K_{sp}<Q_{sp}[/tex]; the reaction is reactant favored.  (Precipitation)
  • When [tex]K_{sp}=Q_{sp}[/tex]; the reaction is in equilibrium. (Sparingly soluble)

As, the [tex]K_{sp}>Q_{sp}[/tex]. The above reaction is product favored. This means that no salt or precipitate will be formed.

Hence, the precipitate will not be formed when these solutions are mixed.