Compound X has a molar mass of 266.68 g/mol and the following composition: aluminum 20.24% chlorine 79.76% Write the molecular formula of X

Al₂Cl₆

Explanation:

Step 1: Divide the mass percentage of each element by its atomic mass

Al: 20.24/26.98 = 0.7502

Cl: 79.76/35.45 = 2.250

Step 2: Divide all the numbers by the smallest one

Al: 0.7502/0.7502 ≈ 1

Cl: 2.250/0.7502 ≈ 3

The empirical formula of the compound is AlCl₃. Its molar mass is 133.33 g/mol.

Step 3: Calculate "n"

n = molar mass of the molecular formula / molar mass of the empirical formula

n = (266.68 g/mol)/(133.33g/mol)

n ≈ 2

Step 4: Determine the molecular formula

We use the following expression.

molecular formula = n × empirical formula

molecular formula = 2 × AlCl₃

molecular formula = Al₂Cl₆