Chemistry Unit- Lesson 12

Lesson 12:
Acids and Bases


First off we made Turmeric Paper. To do this put 1/4 cup alcohol in a bowl and stir in 1/4 tsp of turmeric. Dip coffee filters in the solution until completely covered and yellow. Hang up or place on a cookie sheet to dry.
Once dry, cut them into strips. Now they can be used to test for bases....and acids.
(recipe taken from Janice VanCleave's Chemistry for Every Kid)

Now on to our experiment....

We had a very simple discussion on what acids and bases were. I mentioned that acids have excess hydrogen and bases have excess hydroxide. But mostly we talked about the properties....in terms they know....stomach acid, acid rain, sour, sharp, etc....

We had several solutions to test:
milk, lemon juice, hydrogen peroxide, water, baking soda, borax, saliva, vinegar, bleach water....

One by one we tested them using our turmeric paper....if they produced no change we knew it was not a base...either acid or neutral. If the strip turned red, the solution was basic.

Once we went through all the solutions one time, we retested those solutions that produced no change, but this time we tested them on the strips that were already red. If the strip stayed red....it was most likely neutral. If it turned back to yellow the solution was an acid.

Here's a sample of a basic solution:

Here's a sample of a acidic solution:

Once we ran through our tubes, they went to the kitchen and picked a couple more: apple juice, alcohol and pedialyte.

The results:

acids: lemon juice, peroxide, vinegar, bleach, apple juice and pedialyte
bases: baking soda (with water), borax (with water) and milk
neutral: tap water, alcohol and saliva
_________________

The End
And that concludes our chemistry unit....our 4 weeks are up and we are moving on to Rocks and Minerals....provided I can get it all planned in the next week. We've had a lot of fun with Chemistry though....so we might throw some random experiments in from time to time....