Summary: The anthocyanin in cabbage is used to demonstrate pH differences in household chemicals.
Chemicals and Solutions:
Purple Cabbage. (other fruits & vegetables which work well are radishes, beets, blueberries, grape juice. NOTE: Purple cabbage offers a wide range of colors and is probably the best example if a single indicator is to be used)
array of buffers pH 2-13
household items: vinegar, aspirin, baking powder, ammonia
To make cabbage indicator simply place several cabbage leaves in a blender, add water and puree.
Add indicator to each cylinder in the array of buffers.
The pH of household chemicals can be tested by adding indicator and comparing the color produced to the buffer array.
Note: The indicators tend to deteriorate on standing and should be either freshly prepared or refrigerated if necessary for a day or two. I have frozen them in ice cube trays and they have kept well for several weeks. The indicator is an anthocyanin.
pH1-3 pink 7-up, vinegar, aspirin,lemon juice
pH4-7 purple tap water
pH8 blue soap
pH9 blue green
pH10 green sodium bicarbonate, Rolaids
pH12 & up yellow ammonia, drano