Aldehydes and ketones have lower boiling points than alcohols of similar molar mass because
Correct answer: D. they cannot hydrogen bond to one another, having no hydrogen attached to oxygen
- A. they have smaller molecules
- B. they are non polar
- C. they are ionic
- D. they cannot hydrogen bond to one another, having no hydrogen attached to oxygen
Explanation
Carbonyl compounds are polar and attract one another by dipole to dipole forces, which lifts their boiling points above those of alkanes, but with no O-H bond they cannot form hydrogen bonds between their own molecules and so boil below the corresponding alcohols. They can still accept hydrogen bonds from water, which is why the smaller members are water soluble. Propanone dissolving in water while boiling at only 56 degrees illustrates both points.
Report an error
The more specific you are, the faster it gets fixed. A source beats an opinion.
Prefer email? support@testustad.com
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.
Practise Aldehydes and Ketones
679 free Aldehydes and Ketones MCQs from Chemistry, each with the correct answer and an explanation. Unlimited attempts, no account needed.
Discussion
Stuck on an option, or know a faster way to get there? Ask or explain it here.
No comments yet. Be the first to explain this one.
Exams that ask Chemistry questions like this
Chemistry is on 14 papers prepared for on TestUstad, and all of them draw the same bank, so this question is worth knowing for every one of them.
More Reactivity of Aldehydes and Ketones questions
Which compound gives a positive iodoform test?
Aldehydes and ketones both react with 2,4-dinitrophenylhydrazine to give
Fehling's solution is reduced to a red precipitate of copper one oxide by
Which of the following compounds is a ketone?
Oxidation of an aldehyde with acidified potassium permanganate gives
Benzaldehyde gives a positive test with Tollens reagent but a negative one with Fehling's solution. This shows that