Which of the following will have the highest boiling point ?
Correct answer: D. hexanone
- A. methanol
- B. ethanal
- C. propanal
- D. hexanone
Explanation
Hexanone has the largest carbon skeleton and molar mass among the choices, so its stronger dispersion forces give it the highest boiling point; it also has dipole-dipole attraction from the carbonyl group. The likely mistake is choosing methanol because it forms hydrogen bonds, but hexanone's much larger size outweighs methanol's hydrogen bonding here.
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About Reactivity of Aldehydes and Ketones
The polar carbonyl group makes aldehydes and ketones undergo nucleophilic addition, reduction and condensation reactions. Aldehydes are generally more reactive and oxidise readily to carboxylic acids, whereas ketones resist mild oxidation; reactions with hydrogen cyanide, sodium bisulfite and 2,4-DNP help identify their behaviour.
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