In terms of intermolecular forces, explain why ethanol (C2H5OH, boiling point 78 deg C) has a substantially higher boiling point than propane (C3H8, boiling point -42 deg C), despite having similar molar masses.
Answer and explanation
Correct answer: D. Ethanol forms strong intermolecular hydrogen bonds
- Step 1: Step 1: Ethanol (M = 46 g/mol) and propane (M = 44 g/mol) have comparable molecular sizes and temporary dipole forces. Step 2. Step 2: Ethanol contains a polar O-H bond capable of extensive intermolecular hydrogen bonding. Breaking these strong hydrogen bonds requires far more thermal energy than overcoming propane's weak dispersion forces. Answer: Ethanol forms strong intermolecular hydrogen bonds. Why not the others: Hydrogen bonding dramatically elevates boiling points in alcohols.
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