Source: Extra Practice
A compound contains 4.07% hydrogen, 24.27% carbon, and 71.65% chlorine. If its molar mass is 98.96 g, what is its molecular formula?
Options
Option A
CH2Cl
Option B is correct
C2H4Cl2
Option C
CHCl3
Option D
C2H2Cl4
Explanation
Step 1: Calculate moles: H=4.07/1=4.07, C=24.27/12=2.02, Cl=71.65/35.5=2.02. Ratio C:H:Cl = 1:2:1. Empirical formula is CH2Cl (mass = 12+2+35.5 = 49.5). Step 2: n = Molar Mass / Empirical Formula Mass = 98.96 / 49.5 ≈ 2. Molecular formula = 2 × (CH2Cl) = C2H4Cl2. CH2Cl is the empirical formula, not molecular. CHCl3 and C2H2Cl4 do not match the percentage composition.