Sample Calculation:
A 5.40 g sample of hydrated sodium sulfate, Na2SO4 . xH2O, was found to contain 2.34 g of anhydrous Na2SO4 . This means that the sample had 3.06 g of water (5.40 g - 2.34 g).
Water Content of the Sample:
(3.06 g H2O) x 100 = 56.7% H2O
(Na2SO4 . xH2O)
Molar Ratio Between Na2SO4 and H2O :
Na2SO4 : (2.34 g Na2SO4 ) = 0.0165 mol Na2SO4
(142 g/mol Na2SO4)
H2O : (3.06 g H2O) = 0.170 mol H2O
(18.02 g/mol H2O)
Molar Ratio: (0.0165 mol Na2SO4) : (0.170 mol H2O) = (ratio below)
(0.0165 mol Na2SO4) (0.0165 mol Na2SO4)
Molar Ratio: 1.00 mol Na2SO4 : 10.3 mol H2O