Water Module: Sessions 1-3

 

Water Quality Poll: (Sp. 06. Sp, 07)

 

1.      How concerned are you about pollution of your drinking water?

 

  1. very concerned                     2, 4
  2. somewhat concerned            11, 8
  3. not concerned                       6, 10
  4. unsure                                   0, 1

 

2.  Do you think your water is safe or unsafe?

  1. Safe                                      13, 17
  2. Unsafe                                  3, 2
  3. Unsure                                  3, 3

 

3.       What is the source of most of the water you consume in the average week?

  1. mostly straight from tap        8, 13
  2. mostly bottled or filtered      10, 10
  3. not sure                                 1, 0

 

4.      How satisfied are you with the taste of the water that comes straight out of your tap?

  1. very satisfied                        1, 4
  2. fairly satisfied                       3, 2
  3. just somewhat satisfied         4, 2
  4. not satisfied                          11, 15
  5. not sure                                 0, 0

 

 

What is in the water we drink?

 

                                                         Major      vs         Minor

 

 

            How would you determine “Total Dissolved Solids” in a water sample?

 

 

 

 

            What does the TDS tell you about the source of the water sample?

 

 

 

 

Problem:  Calculate the concentration in M and mM of all the ions in a water sample which contains 400 ppm of TDS if the TDS consists

 

            a) entirely of NaCl (58.5 g/mol)

 

            b) entirely of NaSO4 (142 g/mol)

 

            c) 200 ppm of each of the two salts

                                                                                    Answers

 

What laboratory techniques could you use to quantitatively determine individual components in a water sample?

 

                                                         Major      vs         Minor

 

 

 

            What concentration scales should we employ in our descriptions?

 

 

 

 

 

 

 

 

 

Problems: Nitrate as nitrate or nitrogen?

 

            a) What is the actual concentration of nitrate in DM water which has 8.0 ppm nitrate as nitrogen?

 

 

            b) If an ion selective electrode experiment determines that the nitrate concentration of a sample is 22.8 ppm, what is the nitrate as nitrogen concentration which can be compared to the published water quality guidelines?

 

 

            c) Calculate how much Na2SO4 (142 g/mole) must be added to each of these vessels to yield a solution with each of the following concentration:

 

                                                         100 ml                   100 L                  1 million L

                                                         vol flask                fish tank             swimming pool

            1) 0.100 M sulfate ion

 

            2) 1.0 mM sodium ion

 

            3) 1.0 ppm Na2SO4

 

            4) 1.0 ppb sulfate ion

 

 

                                                            Answers

 

Who decides on what is allowable in your drinking water and at what concentrations?