Testing pH with Purple Cabbage
In our next segment, we’re diving into the fascinating realm of DIY science, where we explore the wonders of a colorful and enlightening experiment. Today, we’re zooming in on how to tap into the power of purple cabbage to measure pH levels. We’re excited to walk you through the subtleties of this natural pH indicator. Join us as we explore the question: How does this vibrant vegetable serve as a DIY litmus test for acidity and alkalinity? Keep watching as we unveil the secrets behind this scientific mystery.
Indeed, it’s possible to measure pH levels in the comfort of your own home using purple cabbage. Let’s quickly go over some basics regarding acidic and alkaline properties. Substances around us, especially liquids, exhibit these traits. Apple juice, oranges, coffee, and milk are all examples of acidic liquids, while baking soda, soapy water, and bleach are alkaline. Acids have a pH below 7, alkaline solutions have a pH above 7, and a balance between the two results in a neutral pH. Pure water has a pH of 7, and the pH of surface water typically ranges between 6.5 and 8.5. The purple cabbage contains a natural indicator that shifts colors depending on the acidity of the solution. In our experiment, we’ll employ red cabbage juice as a pH indicator to assess the pH levels of everyday household liquids. You’ll blend the cabbage juice with different substances and observe the color change brought about by a pigment known as flavin. This transformation will help you identify the approximate pH of the liquid. The pH scale ranges from 0.0 to 14.0, representing the degree of acidity or alkalinity in a liquid. For pH number-color change correlations, refer to the chart provided. Now, let’s kick off our experiment!
Here’s what you’ll need: a head of red cabbage, coffee filters, a funnel or coffee filter basket, a knife, boiling water, a strainer, cups for testing, various solutions to test (like baking soda, lemon juice, vinegar, etc.), and a pitcher or beaker.
The procedure is as follows: Finely chop the cabbage until you have approximately two cups. Put the chopped cabbage into a large beaker or pitcher and pour boiling water over it until it’s covered. Let it sit for about 10 minutes to allow the purple color to be extracted from the cabbage. Then, use your strainer or coffee filter to separate the liquid from the plant material. Allow the cabbage water to cool for 10 minutes before distributing it into different cups, depending on the number of liquids you want to test. Introduce the household solutions to each cup and observe as the colors change according to their pH levels. Use the provided chart to determine whether the substance is an acid or a base and record your findings.
As an additional note, you can create your own pH paper strips by soaking coffee filter paper in the cabbage water and then drying it. Once dried, cut the paper into strips and use them to test solutions by observing the color change. Keep in mind that this experiment can tell you if a substance is acidic or basic, but it won’t provide the exact pH value. This demonstration involves the use of acids and bases.