Does sour mean acid?

The idea

Substances that taste sour tend to contain acids and are acidic in nature.

Four kitchen liquids

Think of lemon, amla, tamarind and vinegar in your kitchen.

What taste do they share?

• Sweet
• Sour
• Salty

Taste clue + litmus test

Each food shows its taste. Test every one with blue litmus and see what the sour ones have in common.

A clue, not a test

Every sour food turned blue litmus red. The sweet and the salty ones did not.

Substances that taste sour tend to contain acids and are acidic in nature.

The word is tend: sour taste is a good clue, and litmus is the real test. But taste a substance only if it is a food that elders say is safe. Never taste a laboratory liquid or an unknown liquid.

Notes

Substances that taste sour tend to contain acids and are acidic. Test with litmus, and never taste lab liquids.

Check yourself

Tamarind water tastes sour. What does it most likely contain?

You dip blue litmus in vinegar, which tastes sour. What do you expect?

A bottle in the laboratory has no label. What is the safe way to find out whether it is acidic?

Sugar solution tastes sweet. What does blue litmus do in it?

• A base. Bases do not taste sour. They tend to taste bitter.
• An acid — correct. Yes! Sour taste tends to mean an acid.
• Neither. Sour is a clue for acids.
• It turns red — correct. Yes! Sour vinegar is acidic, so blue litmus turns red.
• It stays blue. That happens in a base or in neutral liquids.
• It turns green. Litmus changes only between blue and red.
• Taste a drop. Never taste an unknown liquid. It could be harmful.
• Sniff it deeply. Never sniff unknown liquids directly either.
• Dip a blue litmus strip in it — correct. Yes! A litmus strip tells you safely, without tasting.
• It turns red. Sweet is not sour. Sugar solution is not acidic.
• It stays blue — correct. Right! Sugar solution is neutral, so blue litmus does not change.
• It turns colourless. The strip keeps its colour.