Tuesday, June 14th Homework Assignment for Wednesday, June 15th.

ISAS, page 23:

3) The following are three water uses associated with your foul-water laboratory investigation (page 10). Classify each as either a direct or an indirect water use. Explain your answer.

a. Manufacture of the filter paper: indirect water use. The materials needed to make the filter paper, the cooling and running of machinery, and transportation of the filter paper all involve the use of water. Since we do not directly measure this water or recognize filter paper as a product linked to water, the manufacturing of the filter paper is an indirect water use.
b. Premoistening of the sand and gravel: direct water use. Since we must moisten the sand and gravel ourselves and directly measure how much water we add to the cup of sand and gravel, this is a direct water use.
c. Use of water to cool the distillation apparatus: direct water use. Again, since a measurement of water is directly put into the distillation apparatus, this is an example of a direct water use.

4) What does it mean to "purify" water?

To "purify" water is to use various procedures to remove excess materials, such as dirt and other impurities, to produce a "clean", or clear, filtrate. The final state of purification is reached once the clear filtrate is distilled. Even so, distilled water can contain dissolved gases from the atmosphere.

5) Identify at least three techniques for purifying water.

Three techniques for purifying water are oil-water separation, sand filtration, and charcoal adsorption and filtration.

6) What was removed from your foul-water sample in each step of that investigation?

In the first step of the investigation, oil-water separation, oil was removed from my dark brown foul-water sample. In the second step of the investigation, sand filtration, visible solids, such as coffee grounds, was removed from my sample, and the color of the sample became dark yellow. In the third step of the investigation, charcoal adsorption and filtration, all color, most odor, and all (visible) excess sand particles were removed from my foul-water sample.

7) The procedure used in the foul-water laboratory investigation could not convert seawater to water suitable for drinking.
a. Explain why not.
b. What additional purification steps would be needed to make seawater suitable for drinking?

a. Although the procedure used in the foul-water laboratory investigation managed to remove all visible dirt, most odor, and all color from the foul-water sample, by testing electrical conductivity, we discovered that sodium still remained in the water.
b. In order to make seawater suitable for drinking, it would be necessary to separate the salt from the water through distillation. By doing this final purification step, seawater would be fit to drink, but it would not taste very good due to the lack of minerals that are put into water to enhance flavor.

A.8. Page 22:

1) List three water uses that you could do without.

Washing cars, watering the lawn, washing the floors.

2) Identify one activity that you could not do without.

Bathing (assuming the household has just one tub of water--not a large water supply for a shower)

3) For which tasks could you reduce your water use? How?

Shower- by taking quick showers or turning the shower off while applying soap to the body or shampoo to the hair, one could significantly decrease their water use.

4) Impurities added by using water for one particular use may not prevent its reuse for other purposes. For example, you might decide to save hand-washing water and use it later to bathe your dog.
a. For which activities could you use such impure water?
b. From which prior uses could this water be taken?

a. You could use such impure water for washing cars.
b. This water could be taken from saving the water used to wash windows.