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Experiment 10 (red cabbage extract)
Last updated 10-1-07

Question #1: The below two images show the colors that red cabbage pigment has when exposed to solutions of different pH. If the iodized salt is neutral like the distilled water you used, how do the colors in your test tubes compare with the vinegar, salt, and baking soda shown here?
Question #2: Is washing soda alkaline or acidic?  Is vitamin C acidic or alkaline? What is the chemical name for Vitamin C?
Question #3: The top left solution is labeled muriatic acid. Do a google search and tell me would you ever use it around your home. The more modern name for muriatic acid is hydrochloric acid. Do a search for hydrochloric acid MSDS. Report two warnings that are given.

Question 4: Visit the below site and find out what is the chemical name for the pigment that is in red cabbage that allows it to be a pH indicator.

Also name three fruits that could also be used to make a pH indicator.

Finally, the article lists 6 pH levels and their colors. What are they?


Question 5: Read http://www.howstuffworks.com/question439.htm
Roses are red
    Violets are blue,
        Anthocyanins are red
             at the pH of two

   Anthocyanins change color depending on pH. In leaves they are visible when the green chlorophyl goes away in the winter. The acidity of the sap in the leaves will determine how red the leaves become. Use the image search (see arrow) in Google to find picture of something with anthocyanin in it.

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