Question

Mercury chloride is a commercail fungicide. If the molar mass is 470/gl mol and the percent composition is 85.0% Hg and 15.0% Cl, what is the empirical and the molecular formula of the fungicde?

Answer 1

To get the empirical formula:

We know that percentages are 85% mercury and 15% chlorine. Taking a 100 g base:

85 grams Hg

15 grams Cl

We turn them into moles:

85 grams Hg * (1mol / 200.59g) = 0.4237 moles of Hg

15 grams Cl * (1mol / 35.45g) = 0.4231 moles of Cl

We divide each of them by the minimum. As both have almost equal values, we can say that:

Empirical formula = HgCl

For molecular formula:

Molar mass of HgCl = 236.04 g/mol

Molar mass of Mercury Chloride = 470 g/mol

Coefficient of atoms = 470 / 236.04 = 2

So molecular formula will be = Hg₂Cl₂