Planet Earth: Acid Rain

 

1.    Has the acidity (H+ concentration) of rainfall in our area changed during the last 15 years?

 

2.  How do nitrate and sulfate changes compare during this time interval?

 

3.  Is there a relationship to the annual amount of rainfall during this time?

 

 

 

 

        For access to acidity and chemistry data, go to  the National Atmospheric Deposition Program :

http://nadp.sws.uiuc.edu/nadpdata/state.asp?state=MA

(accessible from the Planet Earth web site, follow links to “NASP/NTN Data Access” )

 

For rainfall data, go the National Climatic Data Center:

http://www.ncdc.noaa.gov/cgi-bin/ghcn/precip.ghcncgi

(you may have to look at various charting options)

 

 

For ease of comparison, you can import the data into an Excel spreadsheet to produce graphs from the numerical data. See accompanying instructions for specific ways to do this.


Planet Earth: Measuring pH

 

Part 1: The Concept of “pH”

1.    Line up five glass vials on a sheet of paper, and number their position on the paper from 0 to 4.

2.  In the first vial (#0) put ten drops of food coloring. We will consider this to be a strong acid with a pH = 0.

3.  Take one drop from the vial and put it in the next one (vial #1).  Add nine drops of water.

4.  From vial #1, take one drop and transfer it to vial #2. Add 9 drops of clean water.

5.  Continue this process for all 5 vials.

6.  Complete the data sheet below:

 

Container #

0

1

2

3

4

“pH”

0

 

 

 

 

Concentration

1 mole/l

 

 

 

 

Exponential

100 mole/l

 

 

 

 

 

7.  What is the relationship of ”pH” to actual concentration?

 

 

 

 

Note: This worksheet is adapted from the attached exercise developed by the Massachusetts Water Resources Authority for a more general investigation of concentrations in water.


Part 2: Measuring pH

 

On the tables are bottles of vinegar and  dilute sulfuric acid (H2SO4).

 

1.    Using the available pH papers, determine the pH of these solutions.

 

2.  Note the concentration of the sulfuric acid.  Does your pH measurement agree with the conceptual framework for pH established in Part 1?

 

3.  What should the pH of the solutions be if you dilute them by 10 times and 100 times?

 

 

Starting pH

10x dilution

100x dilution

Sulfuric Acid

 

 

 

Vinegar

 

 

 

 

 

4.  Measure the pH of the water samples you brought using the Hach pH kits.

 


Importing  NADP web data into Excel worksheets for graphing

 

1.     At the NADP page accessed from Planet Earth home page, click on “NADP/NTN Data Access”

 

2.     Click on the map for Massachusetts or another state.

 

3.     Click on the specific site you wish to examine.

 

4.     Choose the time period, data type (your choice), format (“tab delimited”) and answer the survey questions on the form.

 

5.     Click on “Get Data.”

 

6.     You may print the data at this point. Use the printer icon, or “Print..” in File Menu. The data can be plotted by hand on graph paper.

 

7.     You may save the data by using “Save As…” in the File Menu. Click OK to save with the displayed file name.

 

8.     Start Excel, and open the saved file from the File Menu. You will need to look at  “all files” in the appropriate place on the dialogue box.

 

9.     Another dialogue box will appear. Choose “delimited”  then click “Next.”

 

10. Choose “tab”, then click “Next.”

 

11. Click “Finish”. Your data should now be in columns on the worksheet.

 

12. Highlight the column with the years. Hit  “Shift + F8” you can then highlight another column, such as H+

 

13. You can now create a chart using the dialogue boxes. A “Scatter” or “Line” chart will show you the information you want, and you can customize the chart as you see fit. The main purpose here is just to see any trends in the data, so don’t get carried away by appearance!