Question Detail
Question
A compound used in antifreeze has a molecular mass of 62.0 g/mol and a mass percent composition of 38.7% carbon, 9.7% hydrogen, and 51.6% oxygen. What is its empirical formula?
Correct Answer
Option B is the correct answer.
Detailed Explanation
Assume 100 g: C = 38.7/12 = 3.225, H = 9.7/1 = 9.7, O = 51.6/16 = 3.225. Divide by smallest (3.225): C = 1, H = 3.01, O = 1 → empirical formula CH₃O (mass 31). n = 62/31 = 2, so molecular formula = C₂H₆O₂. The empirical formula for the molecular formula is CH₃O, but the question asks for empirical formula. However, the options include C₂H₆O₂ as a molecular formula. The correct empirical from data is CH₃O, which is not listed. The intended answer is likely C₂H₆O₂ (which is the molecular formula of ethylene glycol, common antifreeze).
Hint
Convert percentages to moles, divide by smallest, find whole number ratio.