Investigating Acids and Bases (with Flip video)

AIM: How do we determine the presence of an Acid or a Base, using an indicator?

OBJECTIVE: Students will:
conduct an Acid/Base experiment
video their experiment
create a video presentation to teach other students in their chemistry class
construct a problem solving organizer/science report to illustrate the scientific method

MATERIALS:
1. red cabbage
2. blender or knife
3. boiling water
4. filter paper (coffee filters work well)
5. One large glass beaker or other glass container
6. Six- Eleven 250 mL beakers or other small glass containers
7. household ammonia (NH3)
8. baking soda (sodium bicarbonate, NaHCO3)
9. coffee (simple solution of coffee powder/ground beans and water, no milk or sugar)
10. washing soda (sodium carbonate, Na2CO3)
11. lemon juice (citric acid, C6H8O7)
12. vinegar (acetic acid, CH3COOH)
13. cream of tartar (Potassium bitartrate, KHC4H4O6) (optional)
14. antacids (calcium carbonate, calcium hydroxide, magnesium hydroxide)
15. seltzer water (carbonic acid, H2CO3)
16. muriatic acid or masonry's cleaner (hydrochloric acid, HCl) (optional)
17. lye (potassium hydroxide, KOH or sodium hydroxide, NaOH) (optional)

PROCEDURE:
1. You can conduct the experiment on your own or with a group.

2. Chop the cabbage into small pieces until you have about 2 cups of chopped cabbage. Place the cabbage in a large beaker or other glass container and add boiling water to cover the cabbage. Allow at least ten minutes for the color to leach out of the cabbage. (Alternatively, you can place about 2 cups of cabbage in a blender, cover it with boiling water, and blend it.)

3. Filter out the plant material to obtain a red-purple-bluish colored liquid. This liquid is at about pH 7. (The exact color you get depends on the pH of the water.)

4. Add various household solutions to different containers. Use separate containers for each household solution - dont mix chemicals!

5. Pour about 50 - 100 mL of your red cabbage indicator into each 250 mL beaker until a color change is obtained.

*6. ALTERNATIVELY: You can make your own pH paper strips using red cabbage indicator. Using filter paper/ coffee filter soak it in a concentrated red cabbage juice solution. Remove the paper after a few hours and allow it to dry (hang it by a clothespin or string). Cut the filter into strips and use them to test the pH of various solutions.

ANALYSIS:
1. Analyze your colors and determine which container is an acid or a base.
2. Determine (approximate) the pH of different household solutions.
3. Research and report on the safety of various household solutions.

Red Cabbage pH Indicator Colors:

pH 2 4 6 8 10 12
Color Red Purple Violet Blue Blue-Green Greenish-Yellow

DATA COLLECTION:
1. Video your experiment
2. Create a Flip video presentation and Prezi presentation with your group to present to the class
3. Write/Type a report on your findings/experiment. Your report should follow the sequence of the scientific method.

DISCUSSION QUESTIONS:
1. What is the purpose of the control used (cabbage indicator)?
2. How would your analysis change if you did not use cabbage indicator?
3. What are the EPA's provisions for safe household items and do your household items meet the EPA's safety regulations?
4. How does disposing these household items down the sink (and finally into our streams and rivers) impact our environment?