15.8 Discussion Week 15 – At Home activity (GRADED ASSIGNMENT)

Instructions

Please review the following instructions and video on how to make your own pH indicator from red cabbage at home! A pH indicator  can be in liquid or paper form, and are added to various solutions to determine the pH value. This red cabbage solution is in liquid form, and will be added directly to some household solutions. How much the color changes can tell you whether something is an acid or a base, as well as the value of the pH. 

Dr Dunn’s Procedure Video (Links to an external site.)

Procedure and Data collection video (see below):

MATERIALS

• 1 head of red cabbage
• Pot to boil water in (or blender)
• Strainer or colander
• Glass bowl
• clear cups or glasses
• Three household liquids to test (choose three of the following: vinegar, baking soda, juices, soaps, clear sodas, sugar, salt). Do not use bleach or ammonia as suggested in the video. Please check with me to use any additional household liquids. If you have solids, please dissolve in ~0.5 – 1 cup of water and dissolve the solid prior to adding the red cabbage juice.
• Something to stir with

PROCEDURE

1. Take your red cabbage and cut off about 2-3 cups (the amount doesn’t need to be exact, the more cabbage, the more indicator you will get).
2. Boil a pot of water and place the cabbage pieces in. Bring the water back to a boil for a 2-3 minutes (you want to see the water turn a purple-blue color). Turn heat off and let sit for at least 10 minutes. (Alternatively, you can also place the cabbage in a blender with water to avoid boiling). 
3. Strain the water out into a glass bowl and let cool to room temperature.
4. Once it has cooled, pour some into clear cups or glasses and add different liquids to test. 
5. Gently stir or swirl the solution and see what happens!

Compound Interest’s Making a pH indicator from Red Cabbage (Links to an external site.)

Discuss your results, post a photo of your three household solutions with the pH indicator added and include answers to the following questions:

• What are the pH values of the three solutions you measured?
• Do all the acids or bases change the indicator the same color? What do you think this means?
• Does adding a larger quantity of an acid or base change the color more?
• Do you see any patterns in what the acids or bases are used for?