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Ksp of Calcium Sulfate and Magnesium Hydroxide

1.) A saturated solution of calcium sulfate can be prepared by diluting 0.29g of CaSC4 to 250mL. what is the Ksp of calcium sulfate?

2.) At pH 10.0, only 0.019g of MgCl2 will dissolve per 1L of solution. What is the Ksp of magnesium hydroxide, Mg(OH)2?

Solution Preview

Okay we start by setting up the equation for CaSO4. We know that CaSO4 is a sparingly soluble salt and so:
CaSO4 <==> Ca+2 + SO4-2 and the equilibrium constant or Ksp will be low which means only a very small amount will dissociate to give Ca+2 and SO4-2
since the question states that the saturated solution can be prepared by dissolving 0.29g in 250 ml it means that this is my maximum solubility or in other words was we call S. we can say that the solubility is 0.29g/250ml or its 0.00116 g/ml
It's better to get the solubility in terms of molarity (moles /l) and so we will have to modify the solubility above

we know ...

Solution Summary

The solution answers the question in a step-by-step process between 200-300 words.