Answer to Question #290965 in General Chemistry for Sha

Question

magnesium carbonate, MgCO3/ forms a hydrate containing 39.1% water of hydration. Calculate the formula of this hydrate containing 39.1 % water of hydration. Calculate the formula of this hydrate

Answer 1

M (MgCO₃) = 84.3 g/mol

M (H₂O) = 18 g/mol

Lets assume, we have 100 g of MgCO₃ · xH₂O.

39.1 g of this mass refers to water.

100 - 39.1 = 60.9 g of this mass refers to MgCO₃.

n (MgCO₃) = m / M = 60.9 / 84.3 = 0.72 mol

n (H₂O) = 39.1 / 18 = 2.2 mol

MgCO₃ : H₂O = 0.72 : 2.2 or approximately 1 : 2. Therefore, the formula of this hydrate is MgCO₃ · 2H₂O.