Question

Calculate the percentage of water of cyrstalisation in MgSo4 .7H2O

Answer 1

MgSO₄.7H₂O = Magnesium Sulphate Heptahydrate

RAM of Mg: 24, S = 32, O = 16, H = 1

Molar Mass =  24+32+(16*4)+7(1*2+16) g

= 24+32+64+(7*18) g

= 246 g

% composition of water = Mass of water in the compound/Molar Mass*100%

= [(7*18)/246]*100%

= 51.21%

I hope this helps.