Question

A hydrated compound has analysis of 18.29% Ca, 32.37%CI, and49.34%H2O. What's its formula?

Answer 1

Answer:

CaCl₂.6H₂O

Explanation:

• If we suppose that the compound has a mass of 100.0 g, it will contain 18.29 grams of Ca, 32.37 grams of Cl, and 49.34 grams of water.

• We can convert the grams of each element to moles by dividing the number of grams by the atomic mass of each element.

No. of moles of Ca = (18.29 g) / (40.0 g/mol) = 0.457 mol.

No. of moles of Cl = (32.37 g) / (35.4 g/mol) = 0.914 mol.

No. of moles of H₂O = (49.34 g) / (18.0 g/mol) = 2.74 mol.

• The no. of moles of (Ca: Cl: H₂O) is (0.457 mol: 0.914 mol: 2.74 mol).

• To obtain the ratio of the elements in the compound, we divide over the lowest no. of moles (0.475).

So the mole ratio of (Ca: Cl: H₂O) is (1: 2: 6).

So, the formula of the compound is CaCl₂.6H₂O.