Science experiments for children are designed to give the child physical examples or theories. They can help explain every day, common science issues. pH (the ability of molecules to attract hydrogen atoms) is far reaching in many common areas.
When planting a garden the pH factor comes into play. When testing water the pH balanced is measured. Our bodies have to maintain the correct pH factor.
The red cabbage pH indicator is a great way for students to create their own pH tester. This allows them to test a number of things and gives them the visual learning tool.
Supplies needed:
*red cabbage
*kitchen grater
*stock pot
*water
*distilled water
*strainer
*glass jar (large)
*small glass testing jars
*baking soda
*Sprite
*white vinegar
*eye droppers
*dish washing liquid
Directions:
1. Grate one half head of cabbage (thin)
2. Fill the stock bot with water and the grated red cabbage. Boil for thirty minutes. The water should turn a deep purple.
3. Stain out the cabbage. Make sure the juice goes into the glass jar. Save the cabbage for dinner. Allow the red cabbage juice to cool before continueing.
4. Make selections of base and acid solutions for testing. This is done by mixing the solutions with some distilled water. Have some distilled water set up in a testing jar to show a neutral or normal pH.
5. Add a few drops of cabbage juice to the solution. Make careful notes of the color changes in each glass testing jar. Watch for the color change.
The test solutions that are acidic will turn a light pink. The base solutions will turn green when the red cabbage juice pH indicator is added.
Why does the red cabbage work? Red cabbage has pigments called anthocyanins. This is what gives the cabbage its’ red color. Anothocyanines are a part of a family of chemical compounds referred to as flavonoids. These are released into the water when the cabbage is boiled. Anthocyanin molecules change their color depending the pH of their environment.
The pH scales goes from 0 to 6 (acidic), 7 (neutruel) to 8 to 14 (base). The red cabbage indicator will not give the exact value of the pH. In order to have a number reading one would use a quantitative indicator like litmus paper. It might be fun to get litmus paper and assign numbers. Then repeat the project with another batch of red cabbage indicator and see if the results are the same.
Identifying the pH balance helps us to understand many other things. Doctors check for pH balance in the body. Landscapers adjust the pH balance of the soil to create beautiful yards and flowers. Farms that supply the world with food need to pay attention to the pH balance. Aquariums have to be adjusted so the fish will be healthy. This is a good introduction to pH factors.
sources:
http://science.howstuffworks.com/innovation/experiment1.htm
http://www.madsci.org/experiments/archive/859332497.Ch.html
