The more protons you have in a solution, the more acidic it is. If you have a really high concentration of protons, or low pH, it can be very dangerous, reaction-wise. That solution will bond with whatever it can to get more electrons to complete its outermost electron shell. A really low concentration of protons, or high pH, the solution will want more protons, that, again, it will bond with whatever it can and become extremely dangerous.
You want a pH of about 7. That's what we call neutral, and that's what water is, a nice stable amount of protons. You don't need a laboratory supply company to get everything you need to conduct your own litmus test. All you need is a trip to the grocery store. Get yourself a purple cabbage, and some coffee filters.
Cut the raw cabbage into small pieces until you have about a cups worth.
Spread the cabbage evenly on a microwave safe plate.
Microwave the cabbage for 3-5 minutes until the leaves are slightly soft.
Soak up the juices from the cabbage until the coffee filter is completely soaked. If you need more juices, just cook another cup or so of cabbage.
Lay the paper out to dry for and hour or two.
One small cabbage made 10 sheets of litmus paper. When dry, the paper should be a brighter purple than it was when the papers were soaked in the cabbage juice. I cut the papers into strips. I easily got 20 or so strips from one coffee filter.
If the solution turns red or pink, the solution is an acid; or has lots of protons. I used some lime juice as my acid.
If the paper turns blue or green, the solution is a base. I used a mixture of baking soda and water.
Another base is glass cleaner, which contains ammonia.
Now, why does the cabbage juice change colors?
Purple cabbage contains a large amount of anthocyanin; one of the most common pigments in the plant kingdom. It's what makes pansies purple, blood oranges bloody, and autumn leaves turn red. As it happens, anthocyanin changes colors depending on the pH of it's environment; red-pink in acidic solutions, and greenish-blue in basic solutions. The pH of cabbage juice itself is about neutral, so the anthocyanin appears in its neutral color; purple. This all makes sense when you consider that the litmus paper used in labs is made from a similar process. It's infused with a natural dye found in some lichens that change color in much the same way.
Now you can conduct your own real litmus tests at home. While it's not going to help you with much, you may have just enough cabbage left to make a delicious coleslaw. If you have any other ideas for experiments, comment down below.
Enjoy!
