If a compound has molecular formula C6H6 and empirical formula CH, what is the smallest whole-number multiple that relates them?

If a compound has molecular formula C6H6 and empirical formula CH, what is the smallest whole-number multiple that relates them?

• A. 1
• B. 6
• C. 3
• D. 2

Answer: (B)

Empirical formulas show the simplest whole-number ratio of atoms, while the molecular formula is that ratio scaled by an integer. For C6H6, the simplest ratio of carbon to hydrogen is 1:1, so the empirical formula is CH. The greatest common divisor of the subscripts (6 and 6) is 6, so dividing the molecular formula by 6 gives CH. This means the molecular formula is obtained by multiplying CH by 6: CH × 6 = C6H6. Therefore, the smallest whole-number multiplier is 6. If you used 1, 2, or 3, you’d get CH, C2H2, or C3H3, none of which match C6H6.

Empirical formulas show the simplest whole-number ratio of atoms, while the molecular formula is that ratio scaled by an integer. For C6H6, the simplest ratio of carbon to hydrogen is 1:1, so the empirical formula is CH. The greatest common divisor of the subscripts (6 and 6) is 6, so dividing the molecular formula by 6 gives CH. This means the molecular formula is obtained by multiplying CH by 6: CH × 6 = C6H6. Therefore, the smallest whole-number multiplier is 6. If you used 1, 2, or 3, you’d get CH, C2H2, or C3H3, none of which match C6H6.