Red Cabbage pH strips

Red Cabbage pH strips is a cool science experiment which uses simple house-hold items like bleach, water, baking powder and vinegar to demonstrate the acid-base color change by using a naturally available indicator prepared from Red Cabbage. So, be ready to get amazed with the wide color change range shown by this natural indicator.

Safety First! Adult Supervision Required. Don’t Eat/Drink your Experiments, Wear safety goggles where ever required

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Materials and tools required.

In the box

• 400 ml Glass
• Transparent bowls
• Sheets for pH strips
• Red Cabbage flakes
• Measuring Cylinder 10 ml

From Home

• Water
• Vinegar
• Baking Powder
• Bleach
• Washing powder
• Induction Cook-top
• Scissors
• Glass Bowl

Video on Youtube for the Experiment

What to Do!

1. Cut the white sheet into 4 equal parts.
2. Cut rectangular strips out of them
3. The strips will be further dipped in red cabbage juice.
4. Pour 200 ml water in a glass bowl
5. Put the Red cabbage flakes in water. Put on the induction cook-top to heat it.
6. Heat it for 5-7 minutes in medium flame. Your Red cabbage juice is ready.
7. Filter the entire red cabbage juice a strainer.
8. Now dip the strips you have cut earlier in the red cabbage juice.
9. After 5 minutes pull out the strips and let them dry.
10. Your Red cabbage pH strips are ready.
11. Fill four bowls with different liquids.
12. Dip the pH strips one-by-one into the bowl.
13. Observe the bright color change of the pH strips.

Images for Instructions

Working Principle of Red Cabbage pH strips :

In this experiment, the indicator used here is obtained from Red Cabbage. The pigment that gives red cabbage its color is called anthocyanin.  The same pigment is also found in leaves that turn them red or purple in the fall. This water-soluble pigment is also found in apple skin, plums, poppies, cornflowers, and grapes.

Anthocyanin is a good indicator of acids and bases, as we saw from the wide range of changing colors in this experiment. When added to a base, the purplish pigment turns green or yellow. Very acidic solutions will turn anthocyanin to a red color. When added to something that is neutral (neither an acid nor a base), the strip will remain of same color (or maybe turn a little blue) and the basic solutions, having pH more than 7, will give a shade of green or blue, when tested with the pH indicator.  Therefore, it is possible to determine the pH of a solution based on the color it turns the anthocyanin pigments in red cabbage juice.

Actually, the color of the indicator changes in response to changes in its hydrogen ion concentration. Acids will donate hydrogen ions in an aqueous solution and have a low pH, and will turn red, and the opposite is the case with bases.

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