How would you distinguish experimentally between an alcohol and a carboxylic acid?

Distinguishing between an alcohol and a carboxylic acid experimentally can be done through various chemical tests. Here are a couple of simple tests that can help you differentiate between the two:

1. Acidified Potassium Dichromate Test:

» Procedure:

1.1. Take a small amount of the unknown compound.
1.2. Add a few drops of acidified potassium dichromate solution (usually prepared by adding a few drops of concentrated sulfuric acid to a solution of potassium dichromate).
1.3. Warm the mixture gently.
» Observations:

» If the compound is an alcohol, it will be oxidized to a carboxylic acid. The orange color of the dichromate ion (Cr2O7^2-) will change to green as it is reduced to chromium(III) ions (Cr^3+).
» If the compound is a carboxylic acid, there will be no change in color because carboxylic acids do not undergo further oxidation under these conditions.
» Equations:

» For an alcohol: R-OH+[O]→R-COOH+H2O
» For a carboxylic acid: No reaction.
2. Baking Soda Test (Effervescence Test):

» Procedure:

2.1. Add a small amount of the unknown compound to a test tube.
2.2 Add a pinch of sodium bicarbonate (baking soda) to the test tube.

» Observations:

» If the compound is a carboxylic acid, effervescence (bubbling) will occur due to the reaction between the carboxylic acid and sodium bicarbonate, producing carbon dioxide gas.
» If the compound is an alcohol, there will be no effervescence because alcohols do not react with sodium bicarbonate in this way.

» Equations:

» For a carboxylic acid: R-COOH+NaHCO3→R-COONa+CO2+H2O
» For an alcohol: No reaction.
These tests provide a simple way to distinguish between alcohols and carboxylic acids based on their chemical reactivity. It’s important to note that these tests are not exhaustive, and in some cases, additional confirmatory tests may be needed for a conclusive identification.