Homework # 11

ISDS #1-9, 18-22

1. Hydrologic cycle  

2. Natural water purification process

1. Evaporation and condensation removes most dissolved substances

2. Bacterial action converts dissolved organic chemicals into a few compounds

3. Filtration through sand and gravel removes nearly all suspended matter

3. The properties of aluminum hydroxide are directly tied to the flocculation process. Flocculation gets a hold of the suspended particles and moves them to the bottom of a substance, creating a suspension. 

4. Calcium oxide can be added in the final steps of municipal water treatment  to neutralize the acidic water which will raise the water's pH to a proper level.

5. Fluoride is an ingredient found in toothpaste which reduces tooth decay or rotting.  Approximatley 1 ppm of a fluoride ion can be added to municipal water supplies in the last stage of water treatment through the fluoridation process. 

6. An advantage of drinking chlorinated drinking water compared to untreated water is that chlorine kills diseased microorganisms.

7. A disadvantage to using chlorination in water treatment is that chlorine, when added to water, reacts with organic compounds produced by decomposing animal and plant matter to produce substances that can be harmful to human health.

8. Water from a clear mountain stream may require chlorination to make it safe for humans to drink. This is because the water could possibly be contaiminated with bacteria and heavy metal ions which are unsafe for humans to ingest. 

9. a) charcoal filtration 

   b)the use of ozone.

18. If water evaporation suddenly stopped, the Earth's hydrologic cycle would not be able to continue because there would be no way for the water to get into the clouds to be rained down, and the cycle would end.

19. The hydrologic cycle would also not be able to take place if water could not function as both a solid, liquid, and a gas. 

20. The EPA limits the concentration of THMs in minicipal water to 80 ppb because THM is contains chloroform which may cause cancer, so they need to be careful how much of this substance they are using.

21. The steps in the foul water lab are similar to the natural purification of water because they both purify water through charcoal adsorption, sand filtration, and distillation.

22. 

a) 1 day: 1 ppm

b) 1 week: 7 ppm

c) 1 year: 365 ppm