Term 4: Home Experiment

Acid Rain and Indicators       

Purpose

The purpose of the background portion of the project is to learn:

o       The general properties of acids and bases

o       the pH scale

o       the causes and impact of acid rain

o       what indicators are

In the experiment portion of the project you will prepare a homemade indicator and use it to identify household acids and bases.

Directions

Answer the questions to the background portion of the project in the space provided. Please put the answers in bold or a different color to make it easier to read. Attach your lab report to the background section. (You do not need to include the directions for the lab)

Background

Use your textbook, the internet sites given below and any other source you would like, to answer the following questions.

            Good general sites: http://www.geocities.com/CapeCanaveral/Hall/9111/DOC.HTML

                                          http://www.ec.gc.ca/water/en/manage/qual/e_ph.htm

                                           http://dbhs.wvusd.k12.ca.us/webdocs/AcidBase/Acid-Base-Properties.html                                                       

http://encarta.msn.com/media_461535860/Common_Household_Acids_and_Bases.html

1. List four general properties of acids.

2. List four general properties of bases.

3. The strength of acids and bases are measured using a pH scale. The pH scale generally runs from 1-14. What is the range of pH for acids? For bases? What pH represents a neutral solution?

4. Causes of Acid Rain     (http://www.epa.gov/region1/eco/acidrain/causes.html)

            Two of the gases most responsible for acid rain are SO₃ and NO/NO₂ (referred to as NO_x)

1. How does SO₃ form? (Give a natural source and a man-made source.) Give the name and formula of the acid that forms when SO₃ dissolves in the rain?

2. How do NO_x gases form? (Give a natural source and a man-made source.) Give the name and formula of the acid that forms when the NO_x gases dissolve in the rain?

5. Are the SO₂ and NO_x emissions in Massachusetts increasing annually or decreasing? http://www.epa.gov/region1/eco/acidrain/so2noxnetrends.html

6. What is the difference between wet and dry deposition?

       http://www.epa.gov/airmarkets/acidrain/#what

7. What part of the country is experiencing the biggest problem with acid rain i.e. in which part of the country is the pH of rain the most acidic?  http://www.epa.gov/region1/eco/acidrain/images/phlab04.gif

8. How do the emissions of the power plant in Bellingham compare to the emissions of other plants in Massachusetts? http://www.epa.gov/region1/eco/acidrain/powerplants.html

9. Briefly summarize the effects of acid rain on: http://www.epa.gov/region1/eco/acidrain/enveffects.html

      http://www.geocities.com/narilily/trees.html

      http://www.epa.gov/airmarkets/acidrain/effects/index.html

1. lake/pond dwelling animals

2. forests

3. human health

10. What is the purpose of an indicator?  Describe how it works in solutions of different pH.

       11. Two indicators commonly used in the lab are phenolphthalein and litmus. Fill in the following chart indicating the color of phenolphthalein and litmus in acids and bases.

12. Many natural products such as red cabbage juice can be used an indicators. What is the color of red cabbage juice across the pH scale? (from 1-14)  http://chemistry.about.com/library/weekly/aa012803a.htm

13. Many household products contain acids or bases. Identify the acid or base found in the following household products:

Home Experiment

Purpose

To prepare a home-made indicator and use it to predict the pH of some household products.

Materials

Red cabbage (fresh)

Blender or food processor

Drinking glasses/cups or mugs

Lemon juice

Baking soda

Sprite/7-up/club soda or another colorless soda

Vinegar

Ammonia water

Bleach

Aspirin

Antacid (liquid or tablet form)

Salt

Sugar

One of the following: blueberries, red grape skins, brewed tea from tea bags, raspberries, rhubarb, carrot juice, roses, violets, primroses, hydrangeas, cherries, beets, turnip skins, plum skins, radish skins, grape juice concentrate

Procedure: Part 1

1. Place a few cabbage leaves in the blender or food processor.

2. Add about 500 mL of water and blend until the liquid has turned a dark pinkish-purple color.

3. Add some more water until the solution has a rich hue but isn’t extremely dark. If you need to make it darker, add a few more leaves.

4. Since pure water is neutral, you are now seeing the color of the red cabbage juice in a neutral solution. Pour about 50 mL of the solution into 10 cups/glasses/mugs. Add one of the following household products to each cup and record the color of the red cabbage juice. Be sure the rinse the tablespoon after each sample.  Please take a picture of the 10 cups after the household product has been added to the cabbage juice.  You make take other pictures at your own discretion. 

            A. a tablespoon of lemon juice

            B. a tablespoon of baking soda (stir well)

            C. 10 mL of Sprite/7-up/club soda or any clear soda

            D. a tablespoon of vinegar

            E. a tablespoon of ammonia water

            F. a tablespoon of liquid dish soap (stir well)

            G. an aspirin tablet (NOT Tylenol or Advil) that has been crushed in a small amount of water

(Be sure to stir well after mixing it with the red cabbage juice.

H. a tablespoon of liquid antacid or a tablet that has been crushed in a small amount of water

(stir well)

            I. a tablespoon of salt (stir well)

            J. a tablespoon of sugar (stir well)

Procedure: Part 2

Test one of the following for their effectiveness as a natural indicator. Indicate which you used, and its color in the products used in this experiment i.e. lemon juice, vinegar, etc. (letters AàJ above). If you choose something like blueberries, fruit skins or flower petals, blend them in water first like you did with the cabbage leaves. Please take a picture of the 10 cups after the household product has been added to the natural indicator.  You make take other pictures at your own discretion. 

Choices include:

blueberries, red grape skins, brewed tea from tea bags, raspberries, rhubarb, carrot juice, roses, violets, primroses, hydrangeas, cherries, beets, turnip skins, plum skins, radish skins, grape juice concentrate or choose one of your own.

Lab Report

Title

Purpose

Procedure (paragraph form, past tense, passive voice)

Data Tables (from procedure parts 1 & 2)

Pictures of your experiment (from parts 1 & 2)

Conclusion

Based on the research you did on the color of red cabbage juice at each pH, make a table summarizing for each product, whether or not it is an acid, a base, or neutral and what the pH (or range of pH) might be for that product.

How well did your other indicator work?  Compare the effectiveness of this indicator with the cabbage juice indicator.  Explain your rationale.

Do the household products that are acids have anything in common? Do the bases?