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29 9: INDICATORS The container seen on the left in Image #9 contains a base. The one on the right contains an acid. Click on the image to add a few drops of bromothymol blue to each container. V. Describe the results: Base + bromothymol blue Acid + bromothymol blue Now observe what happens when a chemical named phenolphthalein is added to a container of base and to a container of acid. W. Describe the results: Base + phenolphthalein Acid + phenolphthalein X. Phenolphthalein and bromothymol blue have something very obvious in common. What is it? . Both of these chemicals are called indicators. Define indicator in your own words: Suppose you have a mystery liquid in a test tube, and you want to know whether it is an acid or a base. If you were given a dropper bottle of bromothymol blue, how would you determine whether the mystery liquid was acidic or basic? List the steps you would ollow