When an acid meets a base

What happens when an acid meets a base? Activity 2.7:

• Put one drop of lemon juice and about twenty drops of water in a test tube.
• Add a drop of blue litmus solution. It turns red, because lemon juice is acidic.
• Now add lime water (a base) drop by drop, swirling well.
• At some point the red turns blue again.
• Add one more drop of lemon juice and watch what happens.

The colour came back to blue because the solution is no longer acidic. The lime water neutralised the acid.

When an acid and a base are mixed in enough quantity, the result is neither acidic nor basic. This is a neutralisation reaction. It makes salt and water, and gives out heat:

Acid + Base → Salt + Water + Heat

Meet a scientist. Acharya Prafulla Chandra Ray (P.C. Ray) is called the Father of Modern Indian Chemistry. He earned a doctorate in chemistry in the United Kingdom, came back and built up scientific research in India, and in 1901 set up India's first pharmaceutical company (a company that makes medicines). He wrote about the achievements of ancient Indian chemists, and he wanted children taught in their mother tongue.