The yellow that only bases change
Turmeric turns red in bases. Acids and neutral liquids leave it yellow.
A yellow strip
Turmeric (haldi) paper is yellow.
Which kind of liquid do you think turns it red?
What this lesson covers
The idea
The yellow colour of turmeric turns red in basic solutions but stays unchanged in acidic and neutral ones, so turmeric tests for bases but cannot tell acidic from neutral.
A yellow strip
Turmeric (haldi) paper is yellow.
Which kind of liquid do you think turns it red?
- An acidic liquid
- A basic liquid
- A neutral liquid
Turmeric against litmus
Dip turmeric paper and blue litmus in lemon juice, tap water and soap solution. Compare what each strip tells you.
Turmeric finds only bases
The yellow colour of turmeric turns red in basic solutions but stays unchanged in acidic and neutral ones. So turmeric tests for bases, but cannot tell acidic from neutral.
Ashwin used this idea for a greeting card. He coated paper with turmeric paste and let it dry. Then he wrote on it with a basic solution, and red letters appeared!
- Liquid | Turmeric paper | Blue litmus
- Acidic (lemon juice) | stays yellow | turns red
- Neutral (tap water) | stays yellow | stays blue
- Basic (soap solution) | turns red | stays blue
Notes
The yellow colour of turmeric turns red in basic solutions but stays unchanged in acidic and neutral ones. Turmeric tests for bases, but cannot tell acidic from neutral.
Check yourself
Turmeric paper stays yellow in a liquid. What can you say?
Turmeric paper turns red in a liquid. The liquid is...
Lemon juice and tap water both leave turmeric yellow. Which strip tells them apart?
Red letters appear when you write on dry turmeric paper with a liquid. What kind of liquid was it?
- It is not basic — correct. Yes! Only a base turns turmeric red. It could be acidic or neutral.
- It is acidic. It could be, but it could also be neutral. Turmeric cannot tell.
- It is neutral. It could be, but it could also be acidic. Turmeric cannot tell.
- acidic. An acid leaves turmeric yellow.
- neutral. A neutral liquid leaves turmeric yellow.
- basic — correct. Yes! Red turmeric is the sign of a base.
- Red litmus. Red litmus stays red in both an acid and a neutral liquid.
- Blue litmus — correct. Yes! It turns red in lemon juice and stays blue in tap water.
- Another turmeric paper. It will stay yellow in both, just like the first one.
- Basic — correct. Yes! Only bases turn turmeric red, for example soap solution.
- Acidic. An acid would leave the paper yellow, so no letters would show.
- Neutral. A neutral liquid would leave the paper yellow too.