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Percent Water in a Hydrate

(Molar Mass, Molecular Weight, Gram Formula Mass)

Reading Compounds that have water attached (hydrates)

The • represents CuSO₄ that has 5 waters attached.

CuSO₄• 5H₂O

Cu 1 x 63.55 = 63.55	Add them up Molecular Weight=249.694g/mol rounds to 249.7g/mol water = 5 x 18g/mol
S 1 x 32.07 = 32.07
H 10 x 1.00794 = 10.0794
O 9 x 15.9994 = 143.9946

5 x 18	x 100%	= 36.0%
249.7

CaCl₂ • 2H₂O

Ca 1 x 40.078 = 40.078	Add them up Molecular Weight=147.00856g/mol rounds to 147.0g/mol water = 2 x 18g/mol
Cl 2 x 35.453 = 70.906
H 4 x 1.00794 = 4.03176
O 2 x 15.9994 = 31.9988