Calculating the molarity of ions

[Turquoise]

1. The problem statement, all variables and given/known data
When a reaction mixture with a total volume of 4 L that contains 9.99 g of solid CaSO4 was stoichiometrically produced as per the balanced equation with 2.50 L of aqueous Ca2+, what molarity (M) of Ca2+ was required?

Al2(SO4)3(aq) + 3 CaBr2(aq) → 2 AlBr3(aq) + 3 CaSO4(s)


2. Relevant equations
Stoichiometric ratios.


3. The attempt at a solution
Conversion of CaSO4 to mols = 1.36 mols
molar mass = 340.0 mol/L
After this, I don't know how to find the molarity of the Ca2+ ions...

[Borek]

Not sure if I understand what you are asking. I assume you mean you need to know what was molarity of Ca2+ solution if mass of precipitated calcium sulfate was 9.99g.

First - 9.99g is not 1.36 mole.

Second - concentration is moles/volume.

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