Investigating the Cause

1. Investigating the Cause

2. The Problem ahead… • The immediate problem facing those investigating the Riverwood water crisis is to determine if a dissolved substance was responsible for the fish kill. • They must search for evidence of an intolerably high amount of a dissolved substance toxic to fish, or possibly a shortage of dissolved oxygen

3. Solubility of Solids 1. What is a solute? • stuff that is dissolved in another substance 2. What is a solvent? • stuff that dissolves something(solute)

4. Solubility of Solids 3. What is solubility? • the maximum amount of solute that can be dissolved by a solvent • usually measured in grams that can be dissolved per 100 g of the solvent at a particular temperature

5. 4. What happens when a solute hits its solubility limits? • It will appear as if no more solute is being dissolved • In reality it is, but for every bit that dissolves, dissolved stuff will recrystallize, this is called equilibrium

6. 5. If you were to stir it or give it enough time, will more dissolve? • No

7. Solubility of Solids 6. Why is temperature important? • for most solids, the hotter the water(solvent) the more you can dissolve 7. Iced tea/hot tea-which one can you dissolve more sugar in? • the hotter one will dissolve more sugar

8. Solubility of Solids 8. What is a solubility curve? • a graph that shows you how much a solvent(water) can dissolve of a solute over a range of temperature

10. Solubility of Solids 9. Using the graph what is the solubility of KNO3 at 0C? 50 C? 90 C?

12. Solubility of Solids 9. Using the graph what is the solubility of KNO3 at 0C? 50 C? 90 C? • 30 g, 83 g, 190 C

13. Solubility of Solids 10. What is the solubility curve for NaCl like? What does that mean for life on earth?

15. Solubility of Solids 10. What is the solubility curve for NaCl like? What does that mean for life on earth? • almost a straight line, too great a difference in salt concentration would cause harm to water life 11. What is a saturated solution? • when a solvent holds as much solute as it can at a given temperature

16. Solubility of Solids 12. What is an unsaturated solution? • when a solvent can still dissolve more solute 13. How can you tell if a solution is saturated? • added another little bit, if it dissolves it is unsaturated, if it does not it is saturated

17. Solubility of Solids 14. What is a supersaturated solution? • when a solution contains more solute than it can normally hold at a cooler temperature 15. Why are supersaturated solutions so fragile? • any jarring or an addition of more crystals will cause it to recrystallize

18. Solubility of Solids 16. What are two examples of supersaturated solutions? • honey, sugar water used to make Rock Candy

19. Solution Concentration 17. Are dangerous substances dissolved in water always dangerous to us? • no, it depends on how much of the substance is in the water 18. Can “harmless” substances dissolved in water be dangerous for us? • Yes, in high enough concentrations, even “harmless” substances can be dangerous

20. Solution Concentration 19. What is solution concentration? • quantity of solute dissolved in a specific amount of solvent 20. What would a 5% solution of salt water consist of? • (5 g of salt/ 100 g of salt + water) x 100 = 5%

21. Solution Concentration 21. What is another way of reporting this same concentration? • 5 parts per hundred 22. What are some other ways of reporting concentration • parts per thousand, parts per million

22. Dissolving Ionic Compounds 23. What is a good way of picturing what dissolving is like? • like a tug of war 24. What causes an ionic solid substance to dissolve? • if the forces that attract the ions to water is stronger than the force that attracts the ions to each other

23. Dissolving Ionic Compounds 25. Why is water an exceptional dissolver of ionic solids? • water is a VERY polar substance, its oxygen part is very negative while its hydrogen parts are very positive 26. Illustrate how water dissolves NaCl

28. Dissolving salt

31. Hydrated Cl- ion

32. Hydrated Na+ ion

33. Heavy Ion Contamination 27. Where are the metals located on the PT? • on the left side of the zig zag line 28. Where are the nonmetals located on the PT? • on the right side of the zig zag line

34. Heavy Ion Contamination 29. What are four metallic elements essential for human health • Fe, Mg, K, Ca 30. How much of our daily requirements of these elements do we get from drinking water? • 10%

35. Heavy Ion Contamination 31. What are heavy metals? • more massive members of the metal family 32. Why are they of great concern to us? • they can dissolve in water just like the beneficial metals • they are harmful in even small concentrations

36. Heavy Ion Contamination 33. What are three examples of these dangerous metals? • Cd, Pb, and Hg 34. How do they harm us? • they prevent proteins from working properly

37. Heavy Ion Contamination 35. What are some of the symptoms of heavy metal poisoning? • damage to the nervous system, kidneys and liver, mental retardation, and death

38. Heavy Ion Contamination 36. How do they get in our bodies? • they are discharged by factories and car exhausts • accumulate in lakes and streams • accumulate in the tissue of birds and fish • we eat the fish and it accumulates in our bodies

39. Lead 37. In what ways has lead been used? • pottery, car batteries, solder, cooking vessels, pesticides, household paints 38. Why is lead used in paint? • help prevent corrosion

40. Lead 39. How did the Romans use lead? • they constructed lead water pipes • some historians believe that lead in the water contributed to the Fall of the Roman Empire 40. What is the relation between Plumbers and Lead’s symbol? • the Latin name for lead Plumbum, it was even used for pipes in this country in the early 1800’s

41. Lead 41. What are plumbing pipes made up of these days? • copper and plastics(PVC) 42. Why was lead used in gas fuels? • it produced a better burning fuel

42. Lead 43. Why was leaded fuel banned? • the lead was being released as part of the exhaust, going into our atmosphere and finding its way back into the water 44. What is the EPA limit for lead • 0.05 ppm-average US drinking water contains about half of this

43. Mercury 45. What is the only liquid metal at room temperature? • Mercury 46. What does the symbol Hg stand for? • Hydrargyrum or liquid silver

44. Mercury 47. How do we use Hg? • silent light switch, fever and weather thermometers, thermostats, street lamps, flourescent light bulbs, and in some paints 48. In which form is Hg harmful, gas or liquid? • gas

45. Mercury 49. What are some mercury compounds used for? • antiseptics(mercurochrome), fungicides, and pesticides

46. Mercury 50. What is Mad Hatters Disease • during the 18th and 19th century, many Hatmakers became psychotic by using a mercury compound in the making of felt hats, their symptoms were numbness, staggered walk, tunnel vision, and brain damage

47. Mercury • Hg concentrations in the US are very low • biggest trouble is with organic mercury discharged by factories • this stuff settles in the bottom and gets picked up by molluscs • fish eat the molluscs, people eat fish

48. Cadmium 51. What common metal is Cadmium similar to? • zinc 52. What is Cadmium used in? • Photography, galvanized steel, rechargeable batteries(NiCad)

49. Cadmium 53. What are some of the symptoms of Cadmium poisoning? • Headaches, coughing, vomiting 54. In what form is Cd the most dangerous? • When it is inhaled

50. Cadmium 55. What is the number one source for Cd vapors? • Tobacco smoke 56. Is Cd a big problems in US rivers? • No most drinking water contains very little Cd