Cabbage Juice Chemistry: Experiment
“Cabbage Juice Chemistry” is a fun experiment demonstrating how to create an acid/base indicator at home.
Materials Needed:
- a red cabbage to make cabbage juice
- few plain glasses
- white vinegar
- baking soda
- liquids like lemon juice, hand soap or shampoo, or orange juice.
Experiment Steps:
- Chop a red cabbage into fine pieces and place it in a bowl.
- Pour 2 to 3 cups of boiling water over the cabbage and let it soak for at least an hour.
- Use a strainer to remove the cabbage and save the juice.
- Pour some of the purple juice into the glasses.
- Glass 1 – add baking soda and watch the solution turn blue or blue-green.
- Glass 2 – add white vinegar and watch the solution turn pink.
- Try lemon juice and dish soap in another glass and see the colors change!
Science Behind Cabbage Juice Chemistry
What’s A pH Scale?
- pH scale is a way to measure how “sour” or “soapy” a liquid is. It goes from 0 to 14:
- A liquid with a pH less than 7 is an acid and is “sour.”
- A liquid with a pH of more than 7 is a base and is “soapy.”
- A liquid with a pH of 7 is neutral, like water
What Makes Red Cabbage Special?
- Anthocyanins are tiny color-changing superheroes inside the red cabbage.
- Anthocyanin pigments can change color when they mix with different kinds of liquids.
Color-Changing Superheroes:
Anthocyanins react differently depending on the pH of the liquid they mix with:
- Acids (like vinegar and lemon juice) make them red or pink.
- Bases (like baking soda and dish soap) make them green, blue, or yellow.
- Neutral liquids keep them purple.
Fun Facts
Here are some interesting facts about acids & bases:
- Bases often feel slippery or soapy to the touch. Hence, soap and cleaning products are usually basic.
- Bases are used in antacid tablets to neutralize excess stomach acid and relieve heartburn and indigestion.
- Carbonic acid forms when carbon dioxide (CO2) dissolves in water, giving fizzy drinks their bubbles and slightly tangy taste.
- Ant stings contain formic acid, which causes a burning sensation when you get stung.
Review
Let’s quickly recap what we learned about cabbage juice chemistry:
- What is a way to measure how sour or soapy a liquid is? pH Scale
- What is a liquid with a pH of more than 7 called? Base
- What are the tiny color-changing pigments in red cabbage called? Anthocyanins
- What color does purple cabbage juice turn into when mixed with a base? Blue or Green
- What color does purple cabbage juice turn into when mixed with an acid? Pink
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