A flower that tests
Red rose extract is red in acids and green in bases.
Petals as a test
Red rose petals are soaked to make a coloured liquid called red rose extract.
Which colour do you think the extract shows when it meets lemon juice (an acid)?
What this lesson covers
The idea
Red rose extract is an acid-base indicator: it gives a red colour in acidic solutions and a green colour in basic solutions.
Petals as a test
Red rose petals are soaked to make a coloured liquid called red rose extract.
Which colour do you think the extract shows when it meets lemon juice (an acid)?
- Blue
- Red
- Green
Add the extract
Pick a liquid, then add rose extract to it. Watch the colour of the liquid.
Red for acid, green for base
The extract made two different colours. It acts like a litmus paper that you pour in.
Red rose extract is an acid-base indicator: it gives a red colour in acidic solutions and a green colour in basic solutions.
- Red rose extract in... | Colour
- an acidic solution | red
- a basic solution | green
Notes
Red rose extract is red in acidic solutions and green in basic solutions.
Check yourself
Red rose extract is added to vinegar. What colour do you see?
Red rose extract turns green in a liquid. The liquid is...
Rose extract turns green in lime water. Which litmus strip will also change in lime water?
Liquid X turns the extract red. Liquid Y turns it green. Which is acidic?
- Green. Green is the colour in a base. Vinegar is an acid.
- Red — correct. Yes! Acidic solutions make the extract red.
- Blue. Rose extract does not show blue.
- basic — correct. Yes! Green means a basic solution.
- acidic. An acid makes the extract red.
- impossible to say. It can be said: green is the sign of a base.
- Blue litmus turns red. That happens in an acid. Lime water is a base.
- Red litmus turns blue — correct. Yes! A base turns red litmus blue.
- Neither. A base changes red litmus.
- X — correct. Yes! Red means acidic.
- Y. Green means basic.
- Both. They gave different colours, so they are different kinds.