Colours from the kitchen and garden
Some vegetables, fruits and flowers can also be indicators.
Search the kitchen
Litmus comes from lichens and rose extract from petals. Maybe other plant parts can test, too!
Which one is most likely to work as a natural indicator?
What this lesson covers
The idea
Some vegetables, fruits and flowers, such as beetroot, purple cabbage, turmeric, jamun and red hibiscus, can also act as acid-base indicators.
Search the kitchen
Litmus comes from lichens and rose extract from petals. Maybe other plant parts can test, too!
Which one is most likely to work as a natural indicator?
- Purple cabbage leaves
- Table salt
- Tap water
Test the shelf
Drop each item into the acid tube and the base tube. An indicator shows different colours.
Plants are testers
Some vegetables, fruits and flowers, such as beetroot, purple cabbage, turmeric, jamun and red hibiscus, can also act as acid-base indicators.
NCERT also names beetroot and jamun. Plants even test the soil: hydrangea flowers are blue in acidic soil and pink or red in basic soil.
- Plant material | Colour in acid | Colour in base
- Purple cabbage | pink-red | green
- Red hibiscus (gudhal) flower | dark pink | green
- Turmeric | yellow | red
Notes
Some vegetables, fruits and flowers, such as beetroot, purple cabbage, turmeric, jamun and red hibiscus, can also act as acid-base indicators.
Check yourself
Which of these can act as an acid-base indicator?
Which group lists materials that NCERT names as natural indicators?
A gardener finds hydrangea flowers that are blue. What does this suggest about the soil?
Red hibiscus extract is dark pink in lemon juice. What colour will it show in soap solution?
- Sugar solution. Sugar solution looks the same in an acid and a base.
- Red hibiscus flower — correct. Yes! Its extract is dark pink in an acid and green in a base.
- Tap water. Tap water shows no colour change.
- Beetroot, purple cabbage, turmeric, jamun, red hibiscus — correct. Yes! These coloured plant materials can all act as indicators.
- Sugar, salt, tap water. These do not change colour in acids and bases.
- Iron, copper, glass. These are not plant materials and are not indicators.
- It is basic. Basic soil gives pink or red flowers.
- It is acidic — correct. Yes! Acidic soil gives blue hydrangea flowers.
- Nothing at all. The flower colour is a clue, like an indicator.
- Green — correct. Yes! In a base it turns green.
- Dark pink. It stays dark pink only in acids. An indicator changes in a base.
- Yellow. Yellow is turmeric's colour in an acid, not hibiscus in a base.