Question

Describe how a pure dry sample of pure calcium sulfate can be prepared from sodium sulfate as one of the reagents

Answer 1

Dissolve Na2SO4 in water, add Ca(OH)2 to get

Na2SO4(aq) + Ca(OH)2(aq) ==> CaSO4(s) + 2NaOH(aq)
Filter to isolate the CaSO4 solid (it will be in the form of CaSO4.2H2O) and wash thoroughly to remove the NaOH.
Dry the CaSO4.2H2O in an oven and place in a furnace @ 340 C to remove the water and form anhydrous CaSO4.