Lab - Red Cabbage pH Indicators

A cross-section of a cut cabbage.


Learning Intentions

  • To learn how to use red cabbage as a pH indicator
  • To work on your chemistry lab skills


Notes

As a class, we have already made pH indicators out of red cabbage. We discussed some things that made the indicators work better or worse. This lab is your opportunity to put that feedback into practice.


Procedures - Day 1

  1. Using 10.0 grams of red cabbage, make 4 pH indicators that are as sensitive as possible. The buffer solutions we will use to test will have pH's of 3, 5, 7, and 9.
  2. Leave your coffee filter to dry at the side of the class.
  3. Put the boiled cabbage in the container at the front, and clean up all your equipment.

Procedures - Day 2

  1. Put 1 to 3 drops of buffer solution on each pH indicator you made.
  2. Take a single picture, showing all 4 pH indicators, with labels showing which indicator was put in which buffer solution.
  3. Throw all the pH indicators in the garbage, and clean up all your equipment.


Questions

  1. Picture: Attach your picture of the pH indicators.
  2. Procedures: What did you change to try to produce a better pH indicator? Did your changes work? Why or why not?
  3. Future Work: Do you have any other ideas about how to improve the procedures?
  4. Leaf Colour: What colour do you think the leaves would be if you grew red cabbage in:
    1. acidic soil?
    2. neutral soil?
    3. basic (alkaline) soil?

Assessment

  • Picture
    • Includes all 4 pH indicators with labels
  • Procedures
    • Do your changes indicate a good understanding of pH?
  • Future Work
    • Shows thoughtful analysis of your results
  • Leaf Colour

Picture
Procedures
Future Work
Leaf Colour
1. Beginning Missing a lot
Simple
Simple
Very wrong
2. Developing Missing a bit


Some mistakes
3. Applying
4. Extending -
Advanced
Advanced -