Experiments with KVRR Meteorologist Scott Sincoff: Cabbage Indicator
Fun, Easy, Kid-Friendly Science Experiments
This week, Meteorologist Scott Sincoff worked with Concordia Science Academy Coordinator, Dr. Graeme Wyllie to create a Cabbage Indicator.
What you need:
- Ammonia-based Cleaning Solution
- Strainer or Cheesecloth
How to conduct the experiment:
One of the classes of chemicals that we work with in the chemistry lab is called indicators. These change some properties in relation to its environment. There’s lots of fancy indicators of acids and alkalies, but there’s one indicator that you can find easily in your kitchen and that is in the form of a red cabbage.
The first thing we have to do is get the juice and the color out of the cabbage.
Today, we are going to be doing that by making a cabbage smoothie. We do that by throwing the cabbage in a blender – put a good chunk of the cabbage with a little bit of water into the blender and puree it.
We’re going to blend it until all of the juice is removed from the cabbage. We still have some pieces of cabbage that we’re going to call the chunkies. To get rid of the cabbage bits, we run it through either a coffee filter or squeeze the juice out using a cheesecloth. Then you squeeze the juice out using a cheesecloth. The main object is to get as much juice as possible out of the cabbage.
What we’re going to do now is look and see what happens to the colors. We’re going to pour the cababge juice into the cups and we see that the juice is currently a resounding purple color. We’re going to add a little bit of water and put those into the cups. Next, we’re going to grab a couple of chemicals you can normally find laying around the house – vinegar and ammonia. When using ammonia, you may want to have adult supervision.
We’re going to see what happened to the cabbage color when we add our chemicals.
The ammonia, is basic, and that makes the cabbage juice color to turn green. The vinegar is acidic and causes the cabbage juice color to turn pink. Now pour in the other chemical and see what happens. Because this is a reversible reaction, when the other chemical is poured in, colors change according to which property is more prevalent, the acid or the base/alkali.