Answer to Question #101857 in General Chemistry for Patience Adams

Question

A 25.0 gram sample of a hydrate of iron(III) phosphate was heated until no more water was driven off. The mass of the anhydrous salt is 16.9 grams. What is the empirical formula of the hydrate?
FePO4 x ____ H2O

Answer 1

Solution.

$m(H2O) = m(FePO4*xH2O) - m(FePO4)$

m(H2O) = 8.1 g

n(H2O) = 0.45 mol

n(FePO4) = 0.11 mol

$n(H2O):n(FePO4) = 0.45:0.11 = 4.09:1.00$

$FePO4 \times 4H2O$

Answer:

$FePO4 \times 4H2O$