One way to test for pH is by using litmus (pronounced "LITT- muss") paper. It can be purchased at the drug store, at places where they sell swimming pool supplies, or at pet stores where they have aquarium supplies.
Blue litmus paper tests for acids, and it turns various shades of red when dipped into acidic liquid.
Red litmus paper tests for alkalis (bases). It turns various shades of blue when dipped into alkaline liquid.
Remember, we asked each of you to bring four liquids from home so that we can test them. You have lots of good stuff in little bottles and jars.
Make a heading on your paper by putting the word "ACID" on the top at the left, and the word "ALKALI" on the top to the right of the middle, so you can make two lists.
Take off the lids, and do your testing, by dipping a small piece of blue litmus paper into a jar, then writing the name of the liquid under the category into which it belongs. If the blue litmus paper turns red, that means your liquid is acid. If nothing happens, test it with the red litmus paper. If it turns blue, write the name of your liquid in the
"alkali" column.
Surely you've noticed that some acids made the paper redder than others. The dark red means the acid in that liquid is stronger than that in the liquids that turned the blue paper a light color of red. Same with the paper used for testing alkalis--the dark blue is more alkali than the light blue. You can group your liquids again, in the same columns, but this time, putting the stronger ones first on the lists.
Now we'll have a little cooking lesson. Cream of tomato soup is fun to make, and a little science is necessary to make it properly.
Cook one can of whole or diced tomatoes in a large pot until it has boiled a few minutes. Add a little salt, and if you want, a small amount of minced onion.
Of course, to have "cream" of tomato soup, you need to put in some milk.
WAIT! STOP! If you put milk into the tomatoes, the milk will curdle, and be awful. Why do you think that is?
Tomato is acid. Milk is not. They can't be mixed just like that. What do we do, then, to make "cream" of tomato soup? Science has provided us with an answer to this problem.
Baking soda is alkali. Add one teaspoon of baking soda to the tomatoes. Watch it foam! Zowie! Something is happening here! After it cooks awhile, the foam will go away, and now, you can add the milk.
It will not curdle because you neutralized the acid in the tomatoes by adding baking soda. And the soup is lovely, besides!
Explanation:
