Friday, April 16, 2010

General Science: Indicators for acids and bases

This week we learned about acids and bases and three types of indicators you can use to identify them. We began by using red and blue litmus paper to test different household liquids. We were then able to classify them as acids, bases, or neutral. However while litmus paper is useful, it doesn't tell you anything about how strong or weak a base or acid is. So, for example, while baking soda and bleach, the two bases we encountered, score the same on a litmus test, baking soda tastes mildly bitter whereas tasting bleach will land you in the hospital (hypothetically speaking, of course!). We observed that in order to appreciate this without landing in the hospital, pH paper comes in real handy.

Finally we made our own indicator using purple cabbage juice. Cut up some purple cabbage and boil it for a few minutes. The broth comes out this really funky blue color. Try adding it to different liquids - the results are quite dramatic.

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