Red Cabbage extract changes color in acid and base solutions.
name: Anthocyanin works like a natural pH-indicator.
How to Make a Red Cabbage pH Indicator (Extraction of Anthocyanins)
The Sci Guys: Science at Home - SE2 - EP4: Red Cabbage pH Indicator - Acid Base Indicator
by The Sci Guys
Chemistry experiment 25 - Red cabbage pH indicator
How to make a pH indicator using red cabbage
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anthocyanin (violet) -[pH change]→ anthocyanin (colored)
- In this experiment the pH indicator from red cabbage is obtained. The first way to prepare it is by extraction of compounds from red cabbage leaves.
- Boil some water (about 100 ml) and add a few pieces of red cabbage. The more red cabbage is used the more concentrated indicator solution will be obtained.
- Let it boil for about 5-10 minutes until the water becomes colored.
- Filter out the leaves.
- Cool down the solution.
- The second way is to grind red cabbage leaves and separate the obtained liquid. Put the plant material into a blender and add some water. Blend it for a while and then filter it.
- When the indicator is ready you can test it on some household substances. For example: vinegar, baking soda solution, water solution of ammonia, lye, lemon juice.
- Pour the liquid under study into a glass and add some red cabbage indicator. It will change the solution color depending on hydrogen ion concentration in it.
Red cabbage contains anthocyanin. This substance could be used as pH indicator. In acidic solutions it becomes red, in neutral – purple and turns alkaline solutions green. This property of red cabbage allows using its extract to find out whether the liquid under study acidic or alkaline.