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Question

What is the mass percent of water in Zn(NO₃)_2•6H₂O

Answer 1

The mass percent of water is the mass of water divided by the total mass (x100).

Zn = 65.4 g/mol x 1 = 65.4 g

N = 14 g/mol x 2 = 28 g

O = 16 g/mol x 6 = 96 g

Total for Zn(NO₃)₂ = 189.4 g/mol

H = 1 g/mol x 12 = 12 g

O = 16 g/mol x 6 = 96 g

Total for H₂O = 108 g/mol

Total molar mass for Zn(NO₃)₂ - 6H₂O = 189.4 + 108 = 297.4 g/mol

%H₂O = 108 g/297.4 g (x100%) = 36.3%