One chemical that is particularly important to us humans is water. The pH of a chemical can affect the way it behaves. A pH of 7 is known as neutral and includes plain water. More alkaline solutions have higher pH, between 8 and 14, and less protons.
#Red cabbage apple juice ph baking soda free
More acidic solutions have lower pH, between 0 and 6, and more free protons. On a scale of acidity from 0 to 14, pH tells us how much free protons (also known as positive hydrogen ions) are in a substance. One of the ways our talented and passionate Aquarists care for these animals is by checking the pH level of the water in the aquarium tanks. This activity is adapted from an activity that originally appeared in the Celebrating Chemistry issue for Chemists Celebrate Earth Day 2010.At Discovery Place, we get to work with amazing animals every day. When instead a base gets in the water, a different reaction happens that changes the indicator molecule and it looks green. When an acid like lemon juice gets in the water, a reaction makes the indicator molecule change shape and it looks pink. It is blue in neutral substances, like plain water. This pigment is a natural acid-base indicator. Red cabbage contains a chemical called anthocyanin. How can you tell if something is an acid or a base? Acids and bases can change the color of substances called acid-base indicators. Some substances are neutral, meaning they are neither an acid nor a base, like water. An example of a base is baking soda, which you might have used in the kitchen to make cookies and cakes. On the other end of the spectrum are bases. Lemon juice and vinegar are both examples of acids. In the table in the printable PDF, record the item, the color the liquid turns, and if it is an acid, a base, or neutral.Ĭhemists classify substances as acids or bases.To test another item, use a clean cup and fresh indicator liquid.Record the color of the liquid in the cup below.Use a dropper or straw to place several drops of the test liquid into the cup with the indicator.Add about 1 tablespoon of the indicator liquid to a small cup.It will remain purple or blue if the test solution is neutral. The color of the cabbage indicator will change to red or pink if the solution is an acid and it will change to green or yellow if it is a base. Your red cabbage indicator should be dark blue in color. The liquid is your red cabbage indicator. Pour the liquid from the plastic bag into a cup.Hold the bag at the top with one hand and squish the leaves in the water with the other hand for a couple of minutes until the water turns a dark blue.Remove as much air as possible from the bag and seal it. Tear several leaves of red cabbage into small pieces and place into zip-closing plastic bag.The liquids can be safely disposed of down the drain with plenty of water. Wash your hands well before and after the activity.ĭisposal: Dispose of all solid waste in the trash.Be sure to clean up and dispose of materials properly when you are finished with an activity.Tie back long hair, roll up sleeves, and secure loose clothing.Wear Personal Protective Equipment (PPE), such as goggles, safety glasses, or gloves.Read and follow all directions for the activity.Do not eat or drink any of the materials used in this activity.Ages: As written, this activity is suited for ages 8–12.Red cabbage leaves contain a substance called anthocyanin that changes color depending on whether mixed with an acid or a base.Acid-base indicators change color depending on whether they are in acids or bases.Acids and bases are classes of materials that have different properties.How can you use a red cabbage to test and classify substances? Chemistry concepts
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