MDCAT Chemistry MCQ #101

A 5.0 g sample of ethanol (C2H5OH) is combusted. How many moles of O2 are required for complete combustion? (Molar mass of ethanol = 46 g/mol)

MDCAT Chemistry MCQ #101

  1. Question 1

    Q1. A 5.0 g sample of ethanol (C2H5OH) is combusted. How many moles of O2 are required for complete combustion? (Molar mass of ethanol = 46 g/mol)

    • A) 0.11 mol
    • B) 0.34 mol
    • C) 0.54 mol
    • D) 0.75 mol

    Answer: 0.54 mol

    Explanation: Molar mass of ethanol is 46 g/mol. 5.0 g = 0.1087 mol. Balanced equation: C2H5OH + 3O2 → 2CO2 + 3H2O. 3 moles O2 needed per ethanol. Option B fails to multiply by 3.