Question 21
How can you transform colourless solutions into coloured ones using a homemade indicator (Figure 8.11)? Do the activity to find out.
In the activity, you will be making your own indicator solution using red cabbage leaves (Figure 8.12). The colour of the leaves comes from a pigment. This pigment is a natural indicator.
1. Put on safety goggles.
2. Tear a few red cabbage leaves into very small pieces.
3. Place the pieces of cabbage leaves in a large bowl.
4. Add freshly boiled water into the bowl until it is half full.
5. After 15 minutes, use a strainer to remove the pieces of cabbage leaves. Collect the juice and let it cool. This will be your indicator.
6. Choose four or more different household solutions, such as vinegar, window cleaner, sparkling water and clear lemonade. Pour a little of each into a separate glass or small dish.
7. Pour some cooled red cabbage juice into each glass. Observe how the colour of each solution changes.
8. Red cabbage juice typically turns red in acidic solutions, blue-purple in neutral solutions and yellow-green in alkaline solutions. What can you conclude about the solutions you tested? Classify them in a table.
Caution: Be careful when handling freshly boiled water. Ask an adult to help you if needed. Many household cleaners contain alkalis. Handle them with care.
In the activity, you will be making your own indicator solution using red cabbage leaves (Figure 8.12). The colour of the leaves comes from a pigment. This pigment is a natural indicator.
1. Put on safety goggles.
2. Tear a few red cabbage leaves into very small pieces.
3. Place the pieces of cabbage leaves in a large bowl.
4. Add freshly boiled water into the bowl until it is half full.
5. After 15 minutes, use a strainer to remove the pieces of cabbage leaves. Collect the juice and let it cool. This will be your indicator.
6. Choose four or more different household solutions, such as vinegar, window cleaner, sparkling water and clear lemonade. Pour a little of each into a separate glass or small dish.
7. Pour some cooled red cabbage juice into each glass. Observe how the colour of each solution changes.
8. Red cabbage juice typically turns red in acidic solutions, blue-purple in neutral solutions and yellow-green in alkaline solutions. What can you conclude about the solutions you tested? Classify them in a table.
Caution: Be careful when handling freshly boiled water. Ask an adult to help you if needed. Many household cleaners contain alkalis. Handle them with care.
