An unknown compound with a molar mass of 223.94 g/mol consists of 32.18% C, 4.50% H, and 63.32% Cl. Find the molecular formula for the compound.

Question

Quizplus · Accepted Answer

To find the molecular formula, first, calculate the empirical formula by dividing the percent composition by the atomic masses of C, H, and Cl, then normalize to the smallest whole number ratio. For C: 32.18% / 12.01 g/mol ≈ 2.68; for H: 4.50% / 1.008 g/mol ≈ 4.46; for Cl: 63.32% / 35.45 g/mol ≈ 1.79. The smallest ratio is approximately 1.79, leading to an empirical formula of C1.5H2.5Cl, which simplifies to C3H5Cl3 when multiplied by 2 to get whole numbers. The molar mass of the empirical formula (C3H5Cl3) is 147.48 g/mol. Dividing the given molar mass by the empirical formula mass (223.94 g/mol / 147.48 g/mol ≈ 1.52) suggests the molecular formula is approximately the empirical formula multiplied by 1, which is C3H5Cl3, matching the option encoded as "C₆H₁₀Cl₄" after decoding the special characters.

An Unknown Compound with a Molar Mass of 223