CHow can you know if a solution is
acidic or basic when you don't have a
pH indicator at home? We will see how
its easy to manufacture a pH indicator
at home
Materials
- a pan
- a knife
- 3 glasses
- a small bottle
(a bottle in glass is OK)
- a straw
- a half of red cabbages
- various solutions to test: vinegar, water, solution of sodium bicarbonate....
Process
1) cut the half of a red cabbages in small gills
2) Heat in a pan 300ml of water.
3) When the water boil, stop heating and add the gills of cabbages. Wait for 20 minutes. You get a red solution.
4) filter with the strainer and keep your red solution in a small bottle or in a glass bottle .
You manufactured a pH indicatorn very easly. You can keep your solution a long time because you need only some drops to test some solutions.
5) Puts in every glass a different solution and puts in every glass a few drops of red gabbages solution with a straw.
According to the acidic, neutral or basic environment, the juice of red cabbages turn to red, blue or yellow :
acidic environment
neutral
basic
very basic
(vinaigar)
(water)
(sodium bicarbonate)
(soap)
Explanation
The red solution is constituted by anthocyans that is the color pigments of plants. It can be blue, red, mauve, pink or orange. An example of the structural complexity of the anthocyans is given by the A3 ternatins extracted of the blue-purple flowers of Clitoria ternatea. The A3 ternatin stays until now one of the known most complex anthocyans (see picture below).
