Establish the formula for the crystalline hydrate of barium chloride if, upon calcining a salt with

Establish the formula for the crystalline hydrate of barium chloride if, upon calcining a salt with a mass of 36.6 g, the weight loss was 5.4 g.

Given:
BaCl2 * xH2O
m (BaCl2 * xH2O) = 36.6 g
Δm = 5.4 g

Find:
BaCl2 * xH2O -?

Solution:
1) BaCl2 * xH2O – (toC) -> BaCl2 + H2O;
2) M (BaCl2) = Mr (BaCl2) = Ar (Ba) * N (Ba) + Ar (Cl) * N (Cl) = 137 * 1 + 35.5 * 2 = 208 g / mol;
M (H2O) = Mr (H2O) = Ar (H) * N (H) + Ar (O) * N (O) = 1 * 2 + 16 * 1 = 18 g / mol;
3) m (H2O) = Δm = 5.4 g;
4) n (H2O) = m (H2O) / M (H2O) = 5.4 / 18 = 0.3 mol;
5) m (BaCl2) = m (BaCl2 * xH2O) – m (H2O) = 36.6 – 5.4 = 31.2 g;
6) n (BaCl2) = m (BaCl2) / M (BaCl2) = 31.2 / 208 = 0.15 mol;
7) n (BaCl2): n (H2O) = 0.15: 0.3 = 1: 2;
8) The formula for crystalline hydrate of barium chloride is BaCl2 * 2H2O.

Answer: The formula for the crystalline hydrate of barium chloride is BaCl2 * 2H2O.