7.5 – NOTES Inappropriate Levels in Water

C.8 Inappropriate Heavy-Metal Ion Concentration in River? True or False: Many metal ions, like Fe, K, Ca, and Mg are necessary in small quantities to keep us healthy True Heavy metals are so named because they have a very high atomic mass

Not all dissolved metal ions are helpful As they get farther up the food chain, concentrations increase and become more difficult to remove Green chemistry Practices which prevent pollution by eliminating the production and or use of hazardous substances

C.9 Inappropriate pH Levels in River? pH scale – a way to describe how acidic, basic, or neutral a substance is   Most pHs fall in range of 0-14 On the pH scale, each number is 10 times stronger than the number before it Acids Bases Contain H+ ions contain OH- HNO3, H2SO4 NaOH, Ca(OH)2 Litmus paper turns red litmus turns blue pH value of lower than 7 pH values above 7 sour slippery

Strong acids and bases conduct electricity, both are corrosive Rainwater is slightly acidic Drinking water is between 6.5 and 8.5 Fish can survive in pHs of 5-9

C.10 Inappropriate Molecular-Substance Concentration in River? Molecular substances are composed of molecules and don’t dissolve into ions Can exist as solids, liquids, or gases  Most contain all nonmetal components Molecular substances are usually nonpolar, which means they equally share electrons

Electronegativity An atoms ability to attract shared electrons in a bond   The larger the difference, the more likely ions are to form Solubility follows the rule “Like dissolves like” Polar substances will dissolve polar compounds They will also dissolve ionic compounds, due to the similarity of having charges. Nonpolar solvents will dissolve only nonpolar compounds.

C.12 Inappropriate Dissolved Oxygen Levels in Water? How solids dissolve depends on both temperature and quantity; When temperature increases, the solubility will increase Pressure does not affect the solubility of solids; solids are not able to be compressed Gas solubility is affected by both pressure and temperature. An increase in temperature will decrease the solubility of a gas, while an increase in pressure will increase solubility. The effect of temperature on the solubility of a gas is the opposite of the effect on a solid.

C.13 Temperature, Dissolved Oxygen, and Life Fish are cold-blooded, meaning their body temperature changes with the water temperature   A rise in body temperature increases the metabolism, which means an increase in the fish's needs for oxygen and other resources Increased water temperature can come from: Sun Industry – cooling power plants

Too much dissolved oxygen results in too much dissolved nitrogen, which results in gas-bubble trauma in fish (110-124% supersaturated O2 and N2)   Gas bubbles form in blood and tissue of fish Causes blocked blood flow in fish and kills them