Brassica oleracea, more commonly known as red cabbage, is useful as an acid-base indicator owing to the fairly wide range of pH related color changes. It contains water-soluble anthocyanins, which have indicator properties and vivid colors, making it easy to visualize color changes that occur when they are exposed to different pH conditions. In this experiment, we will use the juice from red cabbage as a pH indicator to test common household liquids and determine their pH levels. 6. Testing pH… Making the pH Indicator (this can be done in advance): 1. The use of anthocyanins in red cabbage extracts as pH indicators has long been a popular classroom activity. The cabbage contains a natural pH indicator that changes colors according to the acidity of the solution. Record the color and pH under Buffer for the “Original (Before HCl added)” row. Q8. 3. The juice is prepared by soaking chopped red cabbage in boiling water for at least 10 minutes and then filtering the solution to eliminate any plant material. indicator to the same test tube. This investigation explores further applications of plant-derived dyes including reversible reactions based on oxidation/reduction chemistry and other reactions to illustrate colour changes that are In this case, the chemicals with indicator properties in the cabbage leaves are dissolved in boiling water.] 3. Leave to cool for about 30 minutes. 2. [Note: A solution in this sense simply means a substance dissolved in water. You can try seeing how tap water affects pH by creating one batch of anthocyanin indicator using distilled water, and another batch with tap water. Flowers, fruits and vegetables contain a diverse range of anthocyanins. The Cabbage Indicator Experiment My hypothesis for this experiment is if I put an acid or a base in to a neutral then it will change colors. Liquid: Color Predicted pH Actual pH Water Lemon Juice Baking Soda Shampoo Close the top and let it blend at high power for 30 seconds. (This should provide you with 600-800 ml of cabbage juice.) Write down what color each solution turns the cabbage juice, based on the following pH scale. Red Cabbage as a pH Indicator Making the pH Indicator What You Need: • A red cabbage • A pot of water Procedure: 1. 5. For baking soda, add 1 tsp of baking soda into 2 tsps water. Put the red cabbage leaves into the blender with 800mL of water. The indicator paper works in the same way as the indicator solution itself: the paper changes color when it comes in contact with an acidic or basic substance. Cover the cabbage in water and boil for 20 minutes, allowing the color to leach out of the cabbage (see picture on right). 2. Are the colors the same? Red cabbage juice is a good indicator of pH because it contains flavin, a pigment molecule that changes colors according to the concentration of hydrogen ions in a solution. My hypothesis was correct in assuming that it would change colors with different substances or mixtures. Pour 1Tbsp of cabbage juice into each of the cups, swirling gently. Sieve the water and cabbage into a jug – you will notice that the cabbage liquid is very purple in colour. Distilled water is more likely to have a neutral pH. Add a small amount of each test substance to a separate cup or container, try to keep the amount of test substance the same. The pH of pure water is 7 and the normal range of surface water is between 6.5 and 8.5. Since the anthocyanin indicator needs to have a pH as close to neutral as possible, this is important. Pour the mixture through a strainer into a large container. 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