How much Na2SO4 solution (in L) must be added to initiate the precipitation of CaSO4?

Explanation:

Hello,

In this case, the rest of statement is missing, therefore, it was found to be:

We add 100 ml of 0.01 M Na₂SO₄-solution to 100 ml of 0.02 M CaCl₂-solution. A precipitate of CaSO₄ is formed. What is the (minimal) volume of 0.01 M Na₂SO₄-solution that needs to be added to the mix for the CaSO₄ precipitate to be just dissolved completely? Consider CaSO₄ solubility constant to be 2.5x10⁻⁵

In this case, Ca⁺², SO₄⁻² and H₂O are out interest substance, thus, if we introduce as the additional volume of Na₂SO₄-solution, we've got:

Hence, we have:

Replacing the previous values:

Solving for , we obtain:

Best regards.

let that person have a turn to speak : )