As a start for our chemistry class this academic year, we focused strongly on doing the experiment as well as designing the experiment. My class had decided to do an experiment on the pH changes as a practice. We’ve chosen an already existed experiment to design the questions, and procedure on.

Question: By adding different amount of the solution into the cabbage’s juice affect the pH?

Procedure:

  1. Chop the cabbage into small pieces.
  2. Add boiling water into the pieces of cabbage, then wait for 20 minutes.
  3. Filter out the cabbage solution into beakers.
  4. Make a 1:1 solution of water: cabbage.
  5. Divide the 1:1 solution into 10 beakers, each beaker contains 200ml of the solution.
  6. Add 10ml of baking soda, lemon juice, bleach, coke, detergent into a separate beaker that contains 200ml of the solution.
  7. Observe the reacting color.
  8. Add 20ml of baking soda, lemon juice, bleach, coke, detergent into a separate beaker that contains 200ml of the solution.
  9. Observe the reacting color.
  10. Compare the new color from the 20ml beakers to the color from the 10ml beakers.  

 

  Color 10ml Color 20ml Observation
Baking Soda Dark Blue Dark Blue Color changes starting from the bottom. Eventually evenly diffuse OR a student decide to shake it.
Lime Dark Pink Dark Pink
Bleach Dark Green (seaweed green) Orange
Coca-Cola Light Purple Light Purple
Powder Detergent Solution with water Mixed of dark green and dark blue Mixed of dark green and dark blue

 

Do Differently:

  1. Prepare the cabbage-water solution before class
  2. Make procedures & questions the day before
  3. Have a better way of recording the reaction: could be the color range that can be put into quantitative data (has to be done before class)
  4. Try with a different ratio of water: cabbage solution.

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