Question

Using the Mole: Empirical Formulas, Molecular Formulas, % Composition 2. Find the empirical formulas for the following compounds: a. 77.7 % Fe, 22.3% O b. 70.0% Fe, 30.0% O C. 72.4% Fe, 27.6%O d. 21.8% Mg, 27.9% P, 50.3% O e. 46.2% Mg, 7.69% H, 46.2% O

Answer 1

Answer

Explanation

Given:

% composition: 46.2% Mg, 7.69% H, 46.2% O

What to find:

The empirical formula for the compound.

Solution:

Step 1: converting the percent composition to grams by using a

100 g sample of the compound.

46.2% Mg ---> (42.2/100) x 100 = 42.2 g

7.69% H ----> (7.69/100) x 100 = 7.69 g

46.2% O -----> (46.2/100) x 100 = 46.2 g

Step 2: Use the molar masses of the two elements to convert the masses to moles.

From the periodic table, the molar masses of (Mg =