Q.Give a simple chemical test to distinguish between ethanol and ethyl bromide.

Step 1. Recall the sodium-metal alcohol test (section 11.4.4). Alcohols show their (very weak) acidic character specifically through reaction with an active metal like sodium: 2R-OH + 2Na -> 2R-O-Na + H2, the liberated hydrogen gas serving as a positive test for an alcoholic -OH group.

Step 2. Apply to ethanol. Ethanol, CH3-CH2-OH, has the required -OH group, so it reacts readily with a small piece of sodium metal, visibly effervescing as hydrogen gas is liberated: 2CH3-CH2-OH + 2Na -> 2CH3-CH2-O-Na + H2.

Step 3. Apply to ethyl bromide. Ethyl bromide, CH3-CH2-Br, has no -OH group at all (bromine, not a hydroxyl, is attached to the carbon), so it has no acidic O-H hydrogen for sodium metal to displace, and it shows NO visible reaction (no gas evolution) with sodium metal under these ordinary conditions. …

Applying section 11.4.4's sodium-metal test for an alcoholic -OH group, noting that ethyl bromide has …

• Proposing the Lucas test or FeCl3 test instead, which are designed to distinguish alcohol SUB-TYPES or to identify phenols, not to distinguish an alcohol from an alkyl halide. …