Which of the following organic compounds could be represented by the empirical formula CH2O?

Step 1: Analyze the question The empirical formula is the simplest whole-number ratio of atoms in a compound. We need the compound whose formula reduces to CH2O, which means C : H : O = 1 : 2 : 1.

Step 2: Write the molecular formula of each option and reduce it

• A. Ethanal (CH3CHO): C2H4O. The ratio is 2 : 4 : 1, so the empirical formula is C2H4O. It does not match.
• B. Ethane: C2H6. It has no oxygen, so it does not match.
• C. Ethanol (C2H5OH): C2H6O. The ratio is 2 : 6 : 1, so the empirical formula is C2H6O. It does not match.
• D. Ethanoic acid (CH3COOH): C2H4O2. Divide each subscript by 2 to get CH2O. It matches.

Step 3: Answer Ethanoic acid has the molecular formula C2H4O2. Dividing by the common factor 2 gives CH2O, so its empirical formula is CH2O.

Tip: To find an empirical formula, divide all the subscripts by their highest common factor. Compounds such as methanal (CH2O), ethanoic acid (C2H4O2), and glucose (C6H12O6) all share the empirical formula CH2O. Remember this pattern, because it appears often in WASSCE and JAMB.