Thursday, February 2, 2012

Biology: Acids and Bases

This week we started a new topic:  acids and bases.  First we used litmus paper and pH paper to classify different household liquids.  Then we boiled up some purple cabbage. Cabbage broth has the interesting property of indicating for acids and bases.

The kids added cabbage juice to the different liquids and observed the results. They recorded the color changes and using the pH values, ordered the cups according to where they fall on the scale. They observed that cabbage juice indicates strong acids with pinks, weak acids with purples, neutrals with blues, weak bases with greens, and strong bases with yellows. Finally they were given an unknown liquid, and using their cabbage-pH scale they guessed its pH.


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