Of Cabbages and Colorings

DSC08778Red cabbage. It looks pretty ordinary at first glance, but this week in homeschool we discovered its amazing color-changing potential. From bright pink to purple to blue, cabbage juice is the perfect indicator for watching acids and bases at work. DSC08780 Getting the idea from a book at our local library, we first cut up a medium-sized red cabbage and soaked it in cold water for 45 minutes. We then strained the liquid (we kept the cabbage leaves for coleslaw) and put 1/2 cup into 6 different glasses. DSC08781 From there the fun began! We first put a teaspoon of baking soda into 3 of the glasses and watched the liquid turn a deep blue color. Then we tested out some different items to see what kind of change they would cause in both plain cabbage juice and cabbage juice with baking soda. We started with vinegar and marveled at the color change in both the plain and baking soda glasses. We then moved on to orange juice and soy milk until we used up all 6 glasses. DSC08782After recording their observations, the Younger Fives had time to ponder some of the curious results of the experiment. Why did vinegar turn the cabbage juice one shade of pink and the orange juice turn it a different shade? Why did both the vinegar and OJ turn the blue liquid with baking soda back to purple, the original color of the cabbage juice? We found some online resources to be particularly useful in helping us understand what we observed, especially the following TED-Ed video on acids and bases. https://www.youtube.com/watch?v=DupXDD87oHc   And perhaps the best part of kitchen chemistry is that all the reactants we used were fit for human consumption. The young scientists were adamant that we save some of the cabbage juice to try after the experiment, so that’s what we did. They all agreed that fresh cabbage juice is not the most refreshing drink ever, but they sure had fun picturing the intense shades of pink it would turn once it reached their stomachs! DSC08784


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