Determine the percent water in Cuso4.5H20 to 3 significant figures

Molar mass is the mass of one mole of a substance and is ontained by adding atomic mases of all the constituent atoms and group of atoms.

Atomic masses: Cu = 63.55 g/mol,

S = 32.07 g/mol

O x 4 = 16.00 g/mol x 4 = 64.00 g/mol

H = 1.008 g/mol,

So, H2O = (2*1.008+16.00)*5 = 90.10 g/mol

Molar mass of CuSO4,5H2O = 249.72 g/mol.

Out of that 249.72 grams, 90.10 grams is water,

So, percentage by mass of water in CuSO4,5H2O

= 90.10*100/249.72 = 36.08.

I think this is what you are asking. hope this helps

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