Let’s explore the pH scale through painting!
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• Paint brushes and paint cups
• Goldenrod paper and red cabbage paper, taped together or set next to each other
• Lemon juice
• Baking soda and water
• Borax and water
• Milk of magnesia
• Tomato juice
• Soapy Water
• Various other acidic or basic substances
Place one piece of goldenrod paper and one piece of red cabbage paper in front of each student. Have clear paint cups containing different acidic and basic substances with labels and 1-2 paint brushes inside each paint cup.
1. Have the students use the different materials to paint on their paper, observing the different reactions. They can compare and contrast the color of the actual liquid to the color that shows up on the paper, further noting that the same substance will bring out different reactions in the two types of paper. Encourage them to wipe off their brush before they apply it to the paper, to avoid oversaturating the material.
2. Encourage the students to apply acids to the bright red goldenrod paper and see if an adverse reaction occurs. Can they write secret messages by using acids on the goldenrod paper first and applying the base after?
Students will observe and create chemical reactions using two different types of paper, as well as acidic and basic substances.
(This lesson can serve as an introduction to the pH scale for young learners, but students should not be expected to firmly grasp the difference between acids and bases at the end of this lesson. Rather, it is an investigation into a chemical change and noticing what reactions are taking place in front of them.)
11.A.ECf Make meaning from experience and information by describing, talking and thinking about what happened during an investigation.
Students will describe the effect of different acids and bases on the two different types of paper and make predictions or conclusions about the reaction.
11.A.ECg Generate explanations and communicate ideas and/or conclusions about their investigations
Students will communicate the color changes that happen on the paper, based on which liquid they apply.