Acids and Bases are everywhere around us. This week’s discussion will involve the optional use of a readily available indicator. Please complete one of the following two activities and then respond to the discussion question listed below. (I highly recommend the first option. You will enjoy it!)
(Option 1) Purchase a head of red cabbage from the grocery store.
• Chop the cabbage into small pieces until you have about 2 cups of chopped cabbage. Place the cabbage in a large 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.) You might want to complete this step outside as it can be kind of smelly.
• 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.)
• Add various household solutions to your indicator until a color change is obtained. Use separate containers for each household solution – you don’t want to mix chemicals that don’t go well together!
(Option 2) Alternatively, you can go to:PBS Kids (Links to an external site.) Complete the virtual lab there to learn about the pH of various household products. I recommend doing the first activity if at all possible, as it is more fun!
Complete all of the following:
• Create a chart that shows what household chemicals you tested, the color they each turned when you added the red cabbage juice, and your estimated pH. To get the estimated pH’s refer to the chart shown to the right:**If you completed the virtual lab, you will not be able to give an exact pH. Just state whether it was an acid or a base.
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• What was the most surprising result from all of the chemicals you tested? Were you able to correctly predict any of the results?
• What was the substance you tested with the lowest pH? The highest? Are you surprised to have such strong acids and bases in your house?
• Suppose you have an acid in your house with a pH of 1.2. This means you have a really strong acid in the house. How would you explain the term “strong acid” to someone who is not familiar with chemistry? How would you explain it to someone who is familiar with chemistry but just forgot what that term means?
• How can you apply what you learned from these experiments to your lives?
Sample Solution
