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JAMB Chemistry 2003 Question 47

Question 47

Chemical Formulae and Equations

A compound contains 40.0% carbon, 6.7% hydrogen and 53.3% oxygen. If the molar mass of the compound is 180, find the molecular formula. [H = 1, C = 12, O = 16]

  1. A.CH2O
  2. B.C3H6O3
  3. C.C6H12O6
  4. D.C6H6O3
Show the answer and explanation

Answer: C (C6H12O6)

Explanation

Mole ratio C : H : O = 40/12 : 6.7/1 : 53.3/16 = 3.33 : 6.7 : 3.33 = 1 : 2 : 1, so the empirical formula is CH2O (30). 180/30 = 6, giving C6H12O6.