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Lab 10 – Measuring pH

(2-Day Lab) This topic intends to demonstrate basic concepts associated with the measurement of pH. Below, find videos describing the use of a “Universal Indicator” for pH (the natural dye from red cabbage) to identify relative acidity in solutions. Dye, then dry, white coffee filters with cabbage juice. Use Q-tips® – or similar cotton swabs – to apply various household acids and bases to the dyed coffee filters. (CAUTION: some household products are equally as dangerous as chemicals in a lab. Use appropriate care and caution with all chemicals). Allow students to “paint” their coffee filters and make art.

Topic Introduction Material (Day 1)
The Lab Activity (Day 2)

For the Lab, provide each student with a cabbage juice dyed coffee filter, Q-tips, lemon juice, baking soda, hydrogen peroxide, dish soap, and other similar household products. Allow students to “paint” their coffee filter by using household acids and bases. Use and enforce appropriate lab behaviors.

3:02 Teach science with art.

3:10 What is the pH scale | Chemistry for All | FuseSchool

4:34 Make your OWN pH Indicator from Red Cabbage!

2:16 Watercolor Painting Tips – Dabbing with the Brush

1:51 DIY watercolor painting with cotton swabs

Compare Contrast and Debate

Kick-Off Debate Background: Chemistry instructors often have a choice to either use (A) commercial-grade chemistry supplies, or (B) household products. While both approaches can demonstrate chemistry concepts – there are pros and cons with using each approach.

  • Position A: Commercial-grade supplies should be used. They are consistent, proven, and more professional.
  • Position B: Household-type of supplies and products should be used. They are less expensive and more meaningful to students.

Special Notes and Notices

Instructor Emphasis:

  • Lab Emphasis: Devise experiments – use trial/error for colors
  • Science & Engineering PracticePlan and conduct investigations
  • Cross-Cutting Concept: Cause and Effect: Cause and Effect: Mechanisms and explanations