Question

Both aldehydes and ketones contain carbonyl groups. in aldehydes, the carbonyl carbon atom is bonded to a hydrogen atom; whereas, in ketones the carbonyl carbon atom is bonded to another carbon atom. select the true statements about aldehydes and ketones.

Answer 1

Full Question Options (Attached)

Answer:

Option 2, Option 5 and Option 6

Explanation:

Option 1

This option is not correct because formaldehyde is not a liquid in room temperature, rather it exists in the gas phase. While propanal exists in the liquid state at room temperature.

Option 2

Ethanal has a boiling point of 20.2°C while ethane has a boiling point of -89°C. This option is correct.

Option 3

This option is incorrect because the polar carbon-to-oxygen double bond causes aldehydes and ketones to have higher boiling points than those of ethers and alkanes of similar molar masses.

Option 4

This option is wrong because as the carbon chain increases in length, solubility in water decreases. The borderline of solubility occurs at about four carbon atoms per oxygen atom. This means the low carbon numbered ketones are soluble in water.

Option 5

ketones are polar molecules because of the presence of the carbon-oxygen double bond. This option is correct.

Option 6

This option is correct as they can hydrogen bond with water molecules.

Answer 2

Answer;

Both aldehydes and ketones can hydrogen bond with water molecules. ethanal has a higher BP than ethane ketones are polar molecules

Explanation;

• An aldehyde differs from a ketone by having a hydrogen atom attached to the carbonyl group, which makes aldehydes very easy to oxidise.
• Ketones lack hydrogen atom and are resistant to oxidation and are only oxidised by powerful oxidising agents which have the ability to break carbon-carbon bonds.
• Both aldehydes and ketones are polar molecules because of the presence of the carbon-oxygen double bond, which means they can form hydrogen bonds with water molecules.