Common Substances, Acid or Alkali-- the Litmus Test
Probably one of the simplest projects to begin understanding the properties of acids and bases is to determine what commonly encountered materials fall into each camp. This experiment, as delineated by Practical Chemistry, uses litmus paper to test a variety of household materials. Using household liquids such as tap water, deionized water, vinegar, lemon juice, soap, shampoo and others, test each material with both a piece of red litmus paper and a piece of blue litmus paper. If blue litmus paper turns red upon contact with a substance and red litmus paper stays red upon contact with that substance, it is an acid. If red litmus paper turns blue and blue litmus paper stays blue upon contact with the substance, it is alkali.
The Cabbage-Juice Test
The juice of a red cabbage has properties similar to that of litmus paper. It changes color when it comes into contact with an acid or alkali. Boil a head of red cabbage in water for about and hour or so to procure the juice, which will be violet-blue in color. Use an eye dropper or straw to place a few drops of red cabbage juice on a white surface such as a plate or counter top. Add a few drops of another household material, like water, vinegar ro soda. Acidic materials will turn the juice red. Basic, or alkaline, materials will turn the juice green or yellow.
The Effect of Antacid on pH Levels
This experiment, suggested by Pico Techonology, examines the effects of antacid on pH levels of a solution. It requires some handling of potentially dangerous hydrochloric acid so be careful. Begin by crushing an antacid tablet and mixing it with water. Stir the mixture and measure the pH. PH indicators are available commercially, or you can use litmus paper. Now, add a drop or two of hydrochloric acid. Make sure to take proper precautions as this material will burn your skin, and always wear protective goggles and clothing. Measure the pH again. How has it changed? Repeat the experiment using a few different brands of antacid tablet and record your results.
Build A Volcano
Acids and alkalies react when they come into contact with each other. This is why antacid tablets (alkalies) help neutralize runaway stomach acid. A simple way to demonstrate this reaction is to build a vinegar and baking soda volcano. Begin by building and decorating a volcano any way you like. Use a soda bottle as the main body of the volcano. Add a few tablespoons of baking soda to the bottle along with a few drops of red or orange food coloring. Add some vinegar and enjoy the show as the acidic vinegar reacts with the alkaline baking soda and "lava" bubbles out of your volcano.