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Extracting Cabbage Juice

 THIS NEEDS ADULT SUPERVISION AS WE WILL BE HEATING

You will need:
  • some red cabbage leaves
  • a sharp knife or scissors
  • a saucepan or equivalent ( must be able to heat it)
  • a camping stove or cooker

 This is what you do:

  • cut up the red cabbage leaves into pieces of about 1 - 2 cm length
  • place the cabbage in the saucepan
  • add enough water to cover the cabbage + 2 cm
  • heat until boiling
  • reduce the heat and simmer for 5 minutes or until the cabbage water has a strong colour.
  • remove from the heat and allow to cool
  • when cool enough to handle use a sieve to separate the coloured juice from the cabbage
  • divide up the juice into small samples and try adding different substances to produce different colours

 This is what we did!

 This is what we found out

  • Adding acid ( like vinegar or lemon juice) to the cabbage juice gives a red colour..
  • Adding Alkali ( like oven cleaner) gives a green colour.
  • Water is neutral and gives a blue/ purple colour.
  • different strengths of acid and alkali will give a whole range of different shades.

 The tekkie bit..

In this experiment we used water to dissolve the coloured stuff ( pigment) in red cabbage. This made a solution of red cabbage juice.  

A solution is a mixture which is formed when one substance ( "the solute") is dissolved in another (" the solvent") . In this case the red cabbage pigment was the solute and water was the solvent.  

We used a sieve or strainer to separate the boiled cabbage from the solution. The sieve or strainer acted as a filter. 

Red cabbage juice is unusual as it changes colour depending on whether it is in acid, neutral or alkaline conditions. This means it can be used as an ( acid/alkali)  indicator.


 Activity 3. Complete the quiz below

 Going further...

Several different acid/alkali indicators exist. In this post we introduce a few of them and look at the colour changes they give. Universal indicator is similar to cabbage juice in that it gives a range of colours - but neutral solutions give a green colour and purple is alkali. How does this compare with cabbage juice?

2.28 Acids, alkalis and titrations

The pH of everyday substances and their pH values can be found using universal indicator  2.28 Activity 1. The Acid test Acids and alk...
https://www.mychem.co.uk/index.php/igcse-chemistry/inorganic-chemistry/acids-alkalis-and-titrations
Oil and trouble
Cabbage Juice
 

Comments 3

Guest - David Fowkes on Friday, 10 April 2020 14:31

Well done guys. You did very well to get some lovely cabbage solution

Well done guys. You did very well to get some lovely cabbage solution
magnus miller on Sunday, 12 April 2020 18:43

Thank you. My explosion was very big and it went everywhere.

Thank you. My explosion was very big and it went everywhere.
David Fowkes on Wednesday, 15 April 2020 14:20

The question is - how did you make it happen?

The question is - how did you make it happen?
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Sunday, 09 August 2020