Appendix 3: Marble Lather Picture
Purpose: To investigate water polarity, surfactants in action and states of matter, using shaving cream and foamy soap. Students will also observe the movement of food coloring (wetting agent) on different states of matter.
Materials: aerosol shaving cream (white), foam pump soap, paper plate, popsicle craft stick, tooth pick, food coloring, index card (unlined), white printer paper (cut in half).
Procedure: 1) Read the label of the shaving cream and the foamy soap and create a chart with the data from the labels. What are the common ingredients?
2. Place a drop of food coloring in the middle of the index card, observe and record how the drop spreads.
3. Place a drop of food coloring in a small transparent plastic cup with 50 ml of water. Observe and record how the drop spreads.
4. Spray 4 dollops of shaving cream on the paper plate, use the popsicle stick to shape and create a flat surface. Add 5-6 drops of food coloring to the top of the shaving cream. Record how the drop spreads.
5. Take the toothpick and create swirling patterns on the surface of the shaving cream. Press the printer paper on the design you created. What do you observe from the back of the paper?
6. Gently lift the paper off the shaving cream and scrape off the excess as close to the paper as possible. Return the excess to the plate. Observe the front of the paper. Explain.
7. Mix the shaving cream on the plate with the popsicle stick until it is one uniform color. You can add 4 more drops if all the color was absorbed by the paper.
8. Apply a drop of water to the tinted shaving cream, with the dropper. Observe/record.
9. Repeat steps 1-8 with the foamy soap.
Analyze: 1. Compare and contrast the spreading of the food coloring onto clean paper, water, and shaving cream. Explain about the polarity of the food color and the paper.
2. Shaving cream is lather, similar to foam. A foam is a colloid consisting of a gas dispersed within a liquid. (The liquid in shaving cream is water and soap, with larger sized soap particles dispersed in water.) What other common products are foam or lather colloids?
3. Artists have created beautiful marble papers since the middle ages. How do you think an artist's understanding of materials influences his or her work? Explain your answer
(Adapted from Journal of Chemical Education, Classroom Activity #89)
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