Learning objective �To EXPLORE by observing red cabbage indicator colours with different solutions �To EVALUATE by reviewing the limits of different indicators to determine pH of a solution Aim To make and test red cabbage indicator Method 1. Put 2 tablespoons of cut red cabbage into a 250mL beaker 2. Fill with tap water to the near the 150mL line 3. Place beaker on a tripod and gauze above a Bunsen burner 4. Turn Bunsen on to blue flame and heat until the water starts to boil 5. Set up a test tube rack with 5 test tubes 6. Half fill each tube with the following solutions as shown in the table below 7. Citric acid and baking soda are solid so will need a small amount of water added to each tube 8. Turn off the Bunsen burner and leave beaker on top for a few minutes (it will be hot) 9. Use a plastic dropper to take some of the red cabbage juice 10. Put 5- 10 drops in each of the tubes 11. Record the colour changes 12. Extension: If time place a piece of filter paper into a petri dish, pour a small amount cabbage juice on top. Leave in corner of lab with a piece of paper with your name on it. 13. Rinse glassware and return equipment Results Insert a photo of your results Hydrochloric acid Citric acid Water Baking soda Sodium hydroxide Colour (change box colour using right click → table properties) Choose 2 of the following words to describe the solution ● ● Acid/neutral/base Weak/strong Approximate pH ( Discussion questions Litmus indicator only has 2 colours, discuss if red cabbage is a more useful indicator than litmus for determining the strength of an acid or base. Explain when it would be useful to know if an acid or a base is weak or strong. Questions Use the question grid to create 2 questions that you want to find out around acid/bases, pH and indicators. Do not use the same words from the grid for both of your questions. Question 1: Question 2: Research your questions and write down what you find out.
