A base is a chemical that has hydroxide (OH)–, as its negative part, such as NaOH (Na+ and OH–)
- Some chemicals, such as baking soda (NaHCO3), form a base when mixed with water.
- A base indicator is a chemical that changes color when added to a base. If the indicator is dry, such as litmus paper, the paper changes color when a base solution touches the paper.
Litmus Paper: Test for a Base
Purpose: To identify a positive test for a base using litmus paper.
Chemicals Needed
1/4 teaspoon baking soda
1 tablespoon of distilled water
1 strip of red litmus
1 strip of blue litmus
Procedure:
1. Mix the baking soda and water together.
2 . Use the same procedures previously described for testing for an acid.
Procedure:
1. The objective is to place a drop of base on each piece of litmus paper. This can be done by any one of the following procedures:
- Fill an eyedropper with the baking powder solution and place a drop of basic solution on each piece of litmus. Observe any change in the color of the litmus strip.
OR - Stir the baking soda solution with a glass stirring rod, wooden craft stick, or plastic knife. Then touch the wet end of the rod or stick to the strips of litmus paper. Again observe any color changes.
Results: The red litmus turns blue. The blue litmus gets wet and may appear more blue in color.
Conclusion: Red litmus can be used to identify a base. Red litmus turns blue when it touches a base solution.