In an accident in a school lab, a large sample of aqueous sodium hydroxide was split. Which substance when added in excess, is not suitable for neutralizing the alkali spill ?

Question

Accepted Answer

Option 1, Sulphuric acid, is not suitable for neutralizing the alkali spill of aqueous sodium hydroxide in a school lab. Here is a detailed explanation supporting this choice:

1. **Why Option 1 is Correct:**
   - **Exothermic Reaction:** Sulphuric acid reacts with sodium hydroxide in a highly exothermic reaction. This means that a significant amount of heat is released during the neutralization process. In a school lab setting, this heat can pose a safety hazard, potentially causing burns or further accidents.
   - **Concentration and Handling:** Sulphuric acid is a strong acid and is often used in concentrated forms. Handling concentrated sulphuric acid requires special precautions, and any mishandling can lead to severe chemical burns or damage to surfaces and equipment.
   - **Corrosive Nature:** The corrosive nature of sulphuric acid can damage lab surfaces and equipment, making it unsuitable for neutralizing spills in a school environment where safety and preservation of equipment are priorities.

2. **Why the Other Options are Incorrect:**
   - **Oxalic Acid (Option 2):** Oxalic acid is a weaker acid compared to sulphuric acid and reacts with sodium hydroxide in a less exothermic manner. It is more manageable and poses less risk of heat-related hazards.
   - **Citric Acid (Option 3):** Citric acid is a weak organic acid and is commonly used for neutralizing bases due to its mild nature. It reacts with sodium hydroxide without releasing excessive heat, making it safer for use in a school lab.
   - **Sodium Hydrogen Sulphate (Option 4):** Sodium hydrogen sulphate is an acidic salt that can neutralize sodium hydroxide effectively. It is less corrosive and exothermic compared to sulphuric acid, making it a safer alternative for neutralization purposes.

In conclusion, while all the other options can neutralize sodium hydroxide, they do so with less risk and potential hazard compared to sulphuric acid. Therefore, Option 1 is correctly identified as not suitable for neutralizing the alkali spill in a school lab setting.