Answer to Question #189330 in General Chemistry for Mohammed

Question

The mass percent of water in a hydrate of MnCl2 is 36.41%. What is the

formula of the hydrate?

Answer 1

The molecular weight of MnCl2 is 125.84 g/mol. If water is 36.41% of that, then the mass of the compound is:

125.84 / (1 $-$ 0.3641) = 197.9 g/mol

Water contributes:

197.9 $-$ 125.8 = 71.16 g

The mole of that is:

71.16 g (1 mol / 18.01 g H2O) = ~3.95 = ~4.00

So the molecular formula of the hydrate is:

MnCl2•4H2O