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Natural Science - Year II

Unit 36: Lab - Acids and Bases

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Lab Assignment for Unit 36


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Unit 36 Laboratory Activity: Acids, Bases, and the release of gas

Goal: Make an acid-base indicator and use it to measure the acidity of common substances.

Equipment and Materials:

Procedure

  1. Grate the cabbage into the water.
  2. Boil the mix until the water turns dark purple (20-30 minutes).
  3. Pour the mix through the strainer into the glass jar. You now have an acid-base indicator containing a pigment, anthocyanin. You can make litmus paper by soaking strips of coffee filter in the liquid and letting them dry.
  4. Add some drops of cabbage solution to the white vinegar. What happens to the color?
  5. Add some drops of cabbage solution to a solution of baking soda and water. What happens to the color?
  6. Add some drops of cabbage solution to a solution of dishwashing detergent and water. What happens to the color?
  7. Try some other solutions made from common foods or household compounds such as soaps or cleaning fluids.

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