Question

Determine if the statements below are true or false.

1. 1-pentanol is less water soluble than 1-butanol.

2. a blue-green precipitate is produced when there is chromic acid oxidation of an alcohol. The Cr+6 ion is responsible for this blue-green color.

3. methyl alcohol will react slower with sodium metal than 2-propanol.

4. a blue-green precipitate will be produced when t-butyl is treated with chromic acid

5. in order for an alcohol to be oxidized by chromic acid, it must possess a carbinol system.

Answer 1

Ans :-

1. TRUE, 1-pentanol is less water soluble than 1-butanol because with increase in number of carbon the non-polar character in alcohols also increases due to that inter-molecular hydrogen bonding between alcohol molecules and water molecules becomes weaker. So, 1-pentanol is less water soluble than 1-butanol.

2. FALSE, a blue-green precipitate is produced when there is chromic acid oxidation of an alcohol. The Cr⁺⁶ ion is responsible for this blue-green color. Because, its Cr³⁺ ions which is responsible for this blue-green color. In this reaction Cr⁶⁺ (red-orange) reduces to Cr³⁺ (blue-green).

3. TRUE, methyl alcohol will react slower with sodium metal than 2-propanol. Because, primary alcohol i.e. methyl alcohol reacts faster with Na than secondary i.e. 2-propanol and tertiary alcohol.

4. FALSE, a blue-green precipitate will be produced when t-butyl is treated with chromic acid. Because, Tertiary group i.e. t-butyl not oxidized by mild oxidizing agent like chromic acid.

5. FALSE, in order for an alcohol to be oxidized by chromic acid, it must possess a carbinol system. Because, chromic acid will not only oxidized carbinol (CH₃OH) but can oxidized primary as well as secondary alcohols.