Why does chopping an onion makes us cry?
When we cut onion, our eyes start to water out of the blue. It's because of the combination of 2 chemicals present in the onion that makes us cry. Onions are packed with sulphur that gives them pungent flavour. Besides, they contains an enzyme known as synthase. Both the enzymes and the sulphur are kept seperately in the onion cells.
When we cut an onion, synthase is released and it reacts with sulphur. This produces a chemical compound known as syn-Propanethial S-oxide which is volatile in nature. Hence, it readily vaporises and enters our eyes. It then reacts with the moisture in our eyes producing Sulfuric acid (H2SO4).
Sulfuric acid causes burning and itching sensation in our eyes. As a preventive measure against the burning, the tear glands in our eyes start producing tears and we are left with watery eyes
Tips to avoid the tears
- Make sure that you keep your fans off.
- Refrigerate the onion before cutting. By refrigerating, enzymes gets freeze and prevents from reacting with sulphur.
- Lighting a candle or a lamp near the chopping board.
Meanings
1. Volatile: Evaporates easily at normal temperature.
2. Sulfuric acid: A strong acid having chemical formula H2SO4
3. Enzymes: Enzymes are the proteins that accelerates the chemical reactions.