Acids and bases are all around us, all the time. We can find acids in our DNA (in amino acids!), hydrochloric acid (in our stomach!), or, more commonly, in household items like vinegar and fruit. We can also find bases in baking ingredients (baking soda and powder!), household cleaners, and soap! Here is a list of common acids and bases, as well as what they’re used for!
While acids and bases have many uses in the world, it may not always be evident that they’re there. For example, you could pull just about any liquid out of your kitchen cabinet, but would you know if it was and acid or a base, simply by looking at it?
One way to tell whether something has acidic or alkaline properties is by using an indicator. This is something that can change color when in the presence of an acid or a base, and it can let you know this property of the material you’re testing! There are a lot of indicators available on the market, but there are also quite a few you can make at home! We’re going to take a look at one of them today.
RED CABBAGE INDICATOR
Red Cabbage contains special pigments called anthocyanins, that cause the dark purple or red color in the leaves. These pigments will change color in the presence of acids or bases, reflecting either a pink or red in the presence of an acid, or blue, green, or yellow in that of a base. There are other foods that contain these pigments, such as red onions, beets, blueberries, blackberries, and more! For this experiment, we’ll be focusing on the cabbage.
2 cups of red cabbage, finely chopped
Pyrex or other large heat safe bowl
Knife or food processor
Glasses to pour your indicator solution into
A variety of liquids to test (lemon juice, laundry detergent, water, vinegar, household cleaner, baking powder mixed with water, milk, soda water, etc.)
Note: This post contains affiliate links to products.
Chop your red cabbage into small pieces. Put in your bowl, and cover with hot water. Let sit for approximately 10-15 minutes, until the cabbage pieces appear white, and the liquid a dark blue or purple.
NOTE: Boiling cabbage is a stinky endeavor! You can mitigate the smell by setting a cup or bowl of vinegar out next to the cabbage, as it will absorb the odors as it cooks.
Pour your cabbage juice through a strainer, and into your pitcher, sifting out all of the bits of leaves.
Pour your solution into your clean glasses. Then, take a variety of kitchen liquids to test and put one next to each cup. Here, we’ve used vinegar, milk, and household cleaner.
Now get to testing! In this example, household cleaner (Awesome Cleaner from the dollar store) turns our indicator solution into a vibrant green color! Any ammonia based cleaner will change to this color, but we found the awesome cleaner was non-toxic, had no ammonia odors, no abrasive skin sensitivities, and worked just as well!
Testing Your Liquids
We already know that vinegar is an acid, so it might be fun to start there! Mixing baking powder (not soda) with a little bit of water can yield a pretty impressive result. Also, if you do you may notice a fizzy reaction, that’s because, depending on the pH of the substance you’re adding to it, water can act as an acid or a base! Mixing baking soda and cabbage water will result in a dark blue color. Add vinegar to it, and you’ll get a foam explosion that changes color as it reacts! Once it settles down, you’ll have a fantastic density column of acids and bases!
Most of the results you’ll get will be on the pink or blue side of the pH color spectrum. Some stronger household bases, however, can give even more dramatic results, like green! You can use ammonia to achieve this green color. However, we found that using the dollar store cleaner LA Awesome Cleaner, worked just as well, without the skin, eye, and nasal irritation, and the strong odor of ammonia. Because we’re working with different chemicals, it’s important to consider possible reactions. Therefore, a quick look at the MSDS reports for this particular cleaner, yielded that there was virtually no toxicity, nor were there any issues with reactions to other chemicals, or irritations to skin, eyes, or nose.
While the red cabbage indicators pick up a nice range on the pH spectrum, some indicators are more specialized and can have some really cool effects. We found out about this beautiful carnation experiment, and just had to try it for ourselves! This experiment requires the use of a specialized indicator, phenolphthalein, that we had to order online. You can purchase it on sites like Home Training Tools, or Carolina Biological Supply Company, or you can purchase larger bottles on Amazon. If you’d rather buy everything in a stand alone kit, Steve Spangler offers a great one on his site, containing everything you’ll need, including the carnations! This indicator reacts specifically to bases within the 8-10 range on the pH scale.
Special thanks to Payne and Morrison Florists in Glendale for donating the carnations we needed for our experiment, and our televised segment!
Note: Phenolphthalein solution should be handled very carefully! Please wear proper protective clothing when using this substance and take care not to get this on your hands. Store in its tightly sealed container, in a cool, dry location. Use outside. Adult supervision is required.
1. Put on your gloves and safety goggles!
2. Carefully coat the carnation with phenolphthalein, being careful to avoid spilling any on your hands. Allow it to dry for approximately 5-10 minutes.
3. Put some of your cleaner in your spray bottle. Using the mist setting, spray a light coat onto your Carnation. Observe the immediate and beautiful reaction that occurs as the color changes from white to a brilliant pink!
For more on acids and bases and different experiments you can do with them, check out the following experiments and activities!
There are so many fun and creative ways to experiment with acids and bases, especially with common household ingredients! So if you’ve got a budding chemist in your house, get ready to don your lab coats and safety gear, and get to ready to explore properties of matter and chemical science!