Question

Which of the following will not be soluble in sodium hydrogen carbonate?

• A. 2,4,6-trinitrophenol
• B. Benzoic acid
• C. o-nitrophenol
• D. Benzenesulphonic acid

Answer 1

The Correct Option is C

To determine which compound is not soluble in sodium hydrogen carbonate (NaHCO₃), we need to understand the acidity of the given compounds. Sodium hydrogen carbonate is a weak base, and it will only react with sufficiently strong acids.

Let's analyze the given options:

1. 2,4,6-Trinitrophenol: Also known as picric acid, this compound is a strong acid due to the presence of three electron-withdrawing nitro groups. It is soluble in NaHCO₃.
2. Benzoic acid: It is a relatively strong acid and can react with NaHCO₃, forming a soluble salt.
3. o-Nitrophenol: This compound is a weak acid. The presence of only one nitro group, and its position ortho to the hydroxyl group, does not enhance its acidity sufficiently to react with NaHCO₃. Therefore, it is not soluble in sodium hydrogen carbonate.
4. Benzenesulphonic acid: This compound is a strong acid due to the sulfonic acid group, making it soluble in NaHCO₃.

Thus, the compound that will not be soluble in sodium hydrogen carbonate is o-nitrophenol.

The reasoning is based on the acid strength comparison: while NaHCO₃ can neutralize strong acids like 2,4,6-trinitrophenol, benzoic acid, and benzenesulphonic acid, it does not react with weaker acids like o-nitrophenol.