Xiao Nuo students at home to do vinegar with purple kale (purple cabbage), the purple kale cut into thin julienne, add people vinegar, found that the purple vegetable julienne turned red, which inspired her desire to explore. Associated with the chemistry textbook on the acid-base indicator in acid, alkali can show different colors, Xiao Nuo decided to experiment to personally verify that the purple kale juice can be used as an acid-base indicator. Ask the question: Can the juice of purple kale be used as an acid-base indicator? Conduct experiments Xiao Nuo take a few leaves of purple kale in the juicer, power on the leaves will be pressed, after filtration to get the purple juice. Take a small amount of the following list of liquids in different containers, and then sucked 2 drops of a 3 drops of purple kale juice in which to observe the purple kale juice shows the color and record. Questioning through the table above purple kale juice shows the color analysis, Xiao Nuo found that the purple kale juice in are alkaline soap and water, oil and lime water in the net showed blue and green and other different colors, so she thought, purple kale juice shows the color of the different with the liquid alkaline strength related to it?