MATRIC NO : MS2417120120

MATRIC NO: MS2417121683

1. The carbonyl group (C=O) is used to differentiate aldehydes and ketones from other classes of compounds.

2. Suitable tests to differentiate aldehydes and ketones are:

• Tollens’ test

• Fehling’s test

• 2,4-Dinitrophenylhydrazine (DNPH) test

• Iodoform test

3. Unknown Y is an ketone

ii ) Aldehydes and ketones contribute significantly to the scent profiles of perfumes. Aldehydes like benzaldehyde provide a sweet, almond-like fragrance, while ketones such as musk ketone add a musky, long-lasting aroma. These compounds are responsible for enhancing and stabilizing the scent.

ii ) Formaldehyde acts as a preservative in household cleaning products. Its role is to maintain the product's effectiveness over time by preventing the growth of bacteria and fungi. This ensures that the product stays safe and effective for use, even after extended storage.

ii ) Acetone is used both in the manufacture of plastics and as a solvent. It helps in dissolving and forming plastic resins, making the processing of plastic materials quicker and more efficient. Its volatility allows for quick drying in applications like varnishes and adhesives.

Observations are recorded.

The above steps are repeated with benzaldehyde, propanone, and unknown Y.

When M was warmed with alkaline iodine, a yellow precipitate was obtained.

M reacts with 2,4-dinitrophenylhydrazine to give an orange precipitate.

(a) Name the yellow precipitate and write its molecular formula.

The yellow precipitate is tri-iodomethane (iodoform).

Its molecular formula is CHI₃.

(b) What is the functional group present in M?

The reaction with 2,4-dinitrophenylhydrazine (2,4-DNPH) confirms the presence of a carbonyl functional group (C=O).

Since it also reacts with alkaline iodine, it must be a methyl ketone (R-CO-CH₃).

The functional group present in M is ketone (-C=O).

2. Suggest one chemical test to distinguish between propanone from propanal. Explain.

Test: Tollens' reagent (ammoniacal silver nitrate solution)

Explanation:

Propanal (an aldehyde) reacts with Tollens' reagent, producing a silver mirror on the test tube walls due to the oxidation of propanal to propanoic acid.

Propanone (a ketone) does not react with Tollens' reagent because ketones cannot be easily oxidized.

3. Explain why both propanol and propanone are very soluble in water.

Propanol (CH₃CH₂CH₂OH) contains a hydroxyl (-OH) group, which can form hydrogen bonds with water molecules, making it highly soluble.

Propanone (CH₃COCH₃) contains a polar carbonyl (-C=O) group, which also interacts with water molecules via dipole-dipole interactions and hydrogen bonding.

Since both molecules can form strong hydrogen bonds with water, they are highly soluble in water.