Acids and Bases Lesson Plan: What’s the pH scale?

Submitted by: Robert Miller

Grade Levels: 6-8, 9-12

In this lesson plan, which is adaptable for grades 6-12, students use BrainPOP resources to learn about acid-base chemistry. They will test household items to determine what pH is and categorize materials using the pH scale.

Lesson Plan Common Core State Standards Alignments

Students will:

  1. Students will test and categorize household materials using an Acid-Base Scale
  2. Students will experiment using the pH scale

Materials:

  • Lemon juice (citric acid, C6H8O7)
  • Baking soda (sodium bicarbonate, NaHCO3)
  • Household ammonia (NH3)
  • Washing soda (sodium carbonate, Na2CO3)
  • 5 pipets or eye droppers (one for each chemical)
  • 5 containers for various chemicals listed below (one set per table to share)
  • Small plastic condiment cups (5 per pair)
  • One large glass beaker or other glass container
  • Filter paper (coffee filters work well)
  • Red cabbage
  • Boiling water
  • Blender or knife
  • Printed copies of the downloadable resources from this page
  • Access to BrainPOP
  • Vinegar (acetic acid, CH3COOH)
  • Cream of tartar (Potassium bitartrate, KHC4H4O6)
  • Antacids (calcium carbonate, calcium hydroxide, magnesium hydroxide)
  • Seltzer water (carbonic acid, H2CO3)

Vocabulary:

acids; bases; hydronium ions; conduct; carbonic acid; ph scale; distilled water; hydroxide ions

Preparation:

Chop the cabbage into small pieces until you have about 2 cups of chopped cabbage. Place the cabbage in a large beaker or other glass container and add boiling water to cover the cabbage. Allow at least ten minutes for the color to leach out of the cabbage. (Alternatively, you can place about 2 cups of cabbage in a blender, cover it with boiling water, and blend it.)

Filter out the plant material to obtain a red-purple-bluish colored liquid. This liquid is at about pH 7. (The exact color you get depends on the pH of the water.)

Lesson Procedure:

  1. As a class, take the BrainPOP Quiz on acids and bases to see what students already know.
  2. Watch the Acids and Bases BrainPOP Movie, pausing to discuss throughout.
  3. As time allows, explore the interactive features that go along with the movie before, during, or after you watch (Activities, FYI).
  4. Students may work in pairs, sharing chemicals with another pair.
  5. Place one Moby Acid/Base Placemat between each pair. After arranging the five numbered condiment cups accordingly, fill each cup with10 ml of Cabbage Juice Indicator.
  6. Chemicals should be labeled and have their own pipette for adding to Indicator.
  7. Together, have students hypothesize where they think each chemical will fall on the pH scale, based on what they learned from the BrainPOP movie.
  8. Students then follow instructions on labsheet, completing the chart and ordering their chemicals based on provided table above.
  9. Materials may be disposed of down a sink with water.

Extension Activity:

To see this lesson in action, check out BrainPOP Educators Acids & Bases Video Tutorial.

DOWNLOADABLE RESOURCES
acidbase POP labsheet.pdf
Cabbage labsheet.pdf