MCAT Chemistry Question — Hydrogen Bonds
- May 13, 2018
- MCAT Question of the Day
In comparison with 1,2-dihydroxyethane, ethanol has weaker intermolecular hydrogen bonds resulting in:
A. a lower boiling point for ethanol due to weaker intermolecular forces.
B. ethanol being a stronger base.
C. a higher boiling point because ethanol is a higher molecular weight compound than 1,2-dihydroxyethane.
D. weaker intramolecular bonds in ethanol due to overall reduced bonding energy.
Click for Explanation
Ethane-1,2-diol (ethylene glycol) has one more hydroxyl group than ethanol, resulting in greater intermolecular hydrogen bonding. Due to the higher intermolecular forces, ethane-1,2-diol has a boiling point of 200°C in comparison with 78°C for ethanol.
A. a lower boiling point for ethanol due to weaker intermolecular forces. Correct.
B. ethanol being a stronger base. Incorrect, The two hydroxyl groups on ethylene glycol confer greater basicity than the one hydroxyl group of ethanol.
C. a higher boiling point because ethanol is a higher molecular weight compound than ethane-1,2-diol. Incorrect, ethanol is a lower molecular weight compound than ethylene glycol.
D. weaker intramolecular bonds in ethanol due to overall reduced bonding energy. Incorrect, Bond energy does not decrease because of intermolecular hydrogen bonding.
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