My youngest daughter needed a science experiment for school and I suggested we try something that I knew would give us pretty colors.
Red cabbage contains anthocyanin which changes colors based on pH. So we got ourselves a red cabbage, chopped it up and added the juice to various substances. (Science is here.)
The control solution was distilled water and then we tried various other things that were either acids or bases. This particular indicator makes all acids red, but bases range from blue to green to yellow. The colors were more vivid than I expected. The only thing I’d change if we did it again is I’d pour some BIG jars of the indicator liquid (more dilute perhaps) and add our test substances to that, it seems to give more impressive results.
The final array:
And just for me, I wanted to test the pH of some of my soap.
If we repeat this experiment I will use a LOT more solution to get a bigger color impact and I will look for something that will give me green (ammonia perhaps?).