Ingredients
- Some of the following:
Red cabbage, beetroot, turmeric and rubbing alcohol, blueberry jam, grape or cranberry juice. - Different substances to test- some suggestions:
lemon juice, water, baking soda dissolved in water, detergents, milk, various drinks, vinegar
Recipe
Cabbage/Beetroot indicator
Add 1/4 cup grated red cabbage or beetroot to 2 cups water and boil for around 10 minutes or until the water turns purple. You could also chop up the vegetables with the water in a food blender. Strain the liquid and remove the vegetables (you can eat these now if you're a bit weird and want to).
Tea indicator
Make some VERY strong tea and allow to cool.
Turmeric indicator
Mix 1 teaspoon turmeric in 1/4 cup rubbing alcohol (this is quite nasty stuff so be careful and get some help if you're not confident). The alcohol will separate when you add the indicator to whatever you're testing so pour in slowly down the side of the glass.
Blueberry jam indicator
Mix a tablespoon of jam with 1/4 cup of water (more or less water depending on how well your jam mixes in). Strain to get rid of the bits.
Grape juice/ Cranberry juice indicator
Just use the juice as it comes out the carton.
Using the indicators:
Add a bit of indicator to the substance you want to test. (You may need to dilute the substance in some water if its thick or dark in color!). Record the color change and try to decide whether it is acidic or basic. You can use the indicator in solution or soak some blotting or filter paper in the liquid and then allow to dry to make pH strips (don't do this with the turmeric indicator though). You can use this to test stuff by dipping it in to the substance - you can even measure the pH of your own mouth by putting it on your tongue! You can also write invisible messages with vinegar or lemon juice, allow them to dry and reveal them by spraying lightly with indicator solution!
You know when leaves go red and purple in the autumn?
Well this is due to the presence of some substances in the leaves
called anthocyanins, members of the flavonoid group. If leaves
contain acidic sap, the anthocyanins will appear red and if the
sap is less acidic, they will go purple. This occurs because in
an acidic solution there are lots of hydrogen ions and the addition
of hydrogen ions to the anthocyanins alters the wavelength of
light that is reflected by the molecules. White light is made
up of the whole spectrum of colors in the rainbow, all of them
have different wavelengths- the color of something depends on
which wavelengths lights are absorbed and which wavelengths are
reflected and detected by our eyes. In a high pH solution there
are few hydrogen ions and this means the anthocyanin loses hydrogen
ions.
