Answer:
∴molecular formula => C₁₂H₁₈O₆
Step-by-step explanation:
A good calculation sequence to follow for empirical formula is ...
% => grams => moles => mole ratio => reduce mole ratio => empirical ratio
then determine whole number multiple for molecular formula using ...
molecular weight = (Whole Number Multiple)(empirical formula weight)
Applying to your posted problem ...
C: 38.43% => 38.43g => (38.43g/12g·mol⁻¹) => 3.2025 moles C
H: 4.85% => 4.85g => (4.85g/1g·mol⁻¹) => 4.85 moles H
Cl: 56.72% => 56.72g => (56.72g/35g·mol⁻¹) => 1.6206 moles Cl
mole ratio C:H:Cl => 3.2025 : 4.85 : 1.6206
reduced mole ratio => divide mole ratio values by the smaller mole value in the set.
That is, reduced mole ratio = empirical formula ratio ...
=> (3.2025/1.6206):(4.85/1.6206):(1.6206/1.6206) => 2 : 3 : 1
∴ empirical formula => C₂H₃O
empirical formula weight = 2(12) + 3(1) + 1(16) = 43g/mol
Whole no multiple = mol wt / emp wt = 250g/mol / 43g/mol ≅ 6
∴molecular formula => C₁₂H₁₈O₆