Answer:
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
