Color your world with cabbage and learn about chemistry! The terms acid and base describe chemical properties of many things we use everyday. An acid is a substance that donates hydrogen ions, and a base is a substance that accepts hydrogen ions. Sometimes, you can tell if something is an acid or base by the way it tastes. Acids, like vinegar, are generally sour. Bases generally taste bitter. (But heads up — some acids and bases are dangerous, so we don’t recommend tasting unknown substances!) Instead of a taste test, chemists use a pH scale to measure the strength of acids and bases. The lower the number on the pH scale, the more acidic something is. In this project, you’ll test different substances in purple cabbage juice and compare the results to a printable pH scale.

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Purple cabbage juice is a pH indicator, or a substance that changes color when it’s mixed with an acid or base. If you add an acid to the cabbage juice, it turns pinkish red. The more red the solution is, the more acidic that substance is. But if you add a base to the cabbage juice, the solution becomes greenish. Purple cabbage isn’t the only plant with this magical, color-changing property. Beets, blueberries, and hibiscus are also pH indicators!

Connections with Next Generation Science Standards (NGSS)

Matter and Its Interactions 5-PS1-3.

Make observations and measurements to identify materials based on their properties.

Create a pH indicator out of purple cabbage juice and learn how to identify acids and bases in everyday kitchen items.