Question

Methyl amine gives precipitate of hydrated ferric oxide on reaction with ferric chloride in water.

Hint:

Amines, such as methylamine, react with ferric salts (FeCl\(_3\)) to form metal hydroxides, which can then dehydrate to produce ferric oxide, as seen in this reaction.

Answer 1

Methylamine (\(\text{CH}_3\text{NH}_2\)) is a weak base. When it reacts with ferric chloride (FeCl\(_3\)) in the presence of water, it forms a precipitate of hydrated ferric oxide. This occurs due to the basic nature of methylamine, which allows it to react with ferric ions (Fe\(^{3+}\)). The reaction between methylamine and ferric chloride proceeds as follows: 1. Methylamine (\(\text{CH}_3\text{NH}_2\)) acts as a base and reacts with Fe\(^{3+}\) ions from ferric chloride. 2. The reaction produces a complex between the ferric ion and the amine. 3. The resulting complex leads to the formation of ferric hydroxide, which eventually dehydrates to form hydrated ferric oxide (Fe\(_2\)O\(_3\)·xH\(_2\)O), which appears as a precipitate. The reaction can be represented as: \[ \text{CH}_3\text{NH}_2 + \text{FeCl}_3 + \text{H}_2\text{O} \rightarrow \text{Fe}_2\text{O}_3 \cdot x\text{H}_2\text{O (precipitate)} \] This reaction is a typical characteristic of amines reacting with ferric salts, where the basicity of the amine induces the precipitation of metal hydroxides or oxides.