Guided Inquiry Lesson Plan # 9: Acids and Bases
Length of Lesson: Two - three class periods
Scientific Processes Addressed: Observing, Classifying, Communicating, Measuring, Predicting
Science Concepts Addressed: pH
National Standards Addressed: A,B,D,F
Objectives: Students will be able to:
1. Define pH.
2. Draw and label a pH scale.
3. Tell what the pH of different items is.
4. Explain why pH is important to humans and how it effects the environment and our lives.
Materials:
Beakers
Litmus paper
Paper towels
Paper and pencils
Substances to test: lemons, apples, vinegar, shampoo, bananas, water, eggs, Ocean water, milk of magnesia, soap, ammonia,
Any materials that help develop background knowledge about pH such as a textbook, color bar.
Introductory Activity: Introduce and explain what pH is. Draw and label a pH scale.
Example:
pH scale
l--l--l---l---l---l---l---l--l---l--l--l---l---l---l
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14
^
Acid (H3O+) Neutral Alkaline
(Base, OH-)
Establish the pH level for acid, neutral, or alkaline.
Main Activities: Explain to the students what litmus paper is, does, and how to use it. Give the students several pieces of litmus paper that will test pH 1-12 and litmus paper that will test pH 6-8. Test the substances with the litmus paper and compare against a color bar to determine the pH number.
Record the pH level for each substance being tested. Discuss possible reasons for differences in pH level. Test other substances within the room which can include saliva, sweat, juice, soda, etc.
Expected Conclusions: The students should start to develop an understanding of the real life application of the scientific concept of pH. The students should feel comfortable with testing the pH of objects.
Assessment: The students will share their individual lists of tested objects and their pH levels and compare their results with others.
Possible Extensions:
Math-graph the pH levels of several substances tested.
English-A short essay on how pH is used in our everyday lives.
Computer Skills – On the web site www.miamisci.org/ph/ students can further explore testing the pH of various substances.