During experiments, ecosystem maintenance, process regulation, etc. knowing the pH level of the environment is crucial. High tech labs and researchers use complex techniques and indicators for finding pH levels, but it doesn’t have to be hard or expensive for hobby scientists. A simple but effective pH indicator can be made with some red cabbage in a few hours, and I will show you how.

Goal:

This guide will show you how to create a pH indicator using some red cabbage and just a few hours of your time.

Background Info (Theory):

Red cabbage contains a water-soluble pigment called Anthocyanin, which is red. The special ability of this pigment is that it turns bright red when it is added to a solution with a pH under 7 (acidic) and it turns blue when the pH is above 7 (basic).

Materials:

  • A quarter of a red cabbage head or more
  • Two cups of water
  • A pot for boiling
  • A container of some kind

For testing:

  • 0.5 teaspoon of Baking Soda
  • 5 mL of vinegar
  • A well plate or three small bowls/cups

The Procedure:

Step 1 (Red Cabbage Boiling):

The first thing you have to do is adding two cups of water to a cooking pot and then cut the red cabbage into small-medium pieces (important to get a lot of surface area). Then add the cabbage to the cooking pot and set it to boil for about 3 minutes. After the 3 minutes turn the heat off and set the cooking pot aside for half an hour.

Step 2 (Finalizing and Packaging):

When you have the now cool red cabbage and water pour the red/purple water into your container using either a filter or the lid. Now you are pretty much finished creating the pH indicator, yes it was that easy. Now you can either throw out the boiled cabbage or eat it later, that is 100% up to you.

The liquid should look something like this

Step 3 (Testing):

Now that you have your indicator why not test to see if it works?
First add vinegar to one bowl, then baking soda and 5mL of water to another, and then put water in the last one for use as a control. If you have a well plate, like I do, you can use that one. Now the time has come to see the effect of this indicator. Simply add a about 2mL of indicator to each bowl and watch the magic happen. However if you do not see a result, you might have to add more indicator.

I had some indicator strips laying around, and as you can see the pH indicator works perfectly.

Conclusion:

Thank you for reading through this experiment, and I hope that you learned a little bit about pH indicators. If you want to know the specific pH of something using this cabbage indicator, there are hundreds of pH scales online that will work for you. As always if you have any questions or suggestions feel free to comment on this article below.

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