Give a chemical test to distinguish between ethylamine and aniline.

Explanation

To distinguish between ethylamine and aniline, we can use the Azo dye test, which is based on their different reactions with nitrous acid (HNO2). Here’s a step-by-step solution:

### Step 1: Understand the Compounds
- Ethylamine (C2H5NH2) is an aliphatic amine, while aniline (C6H5NH2) is an aromatic amine. This structural difference is key to their reactivity with nitrous acid.

### Step 2: Prepare Nitrous Acid
- Nitrous acid can be prepared in situ by reacting sodium nitrite (NaNO2) with hydrochloric acid (HCl) at low temperatures (0-5 °C).

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