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Unit 1 Section C. Investigating the Cause of the Fishkill. Water is the universal solvent It doesn’t dissolve everything, but more than most other solvents Why? Water is a polar molecule It has electrical properties It is held together with covalent bonds. Lets Talk about Water.
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Unit 1 Section C Investigating the Cause of the Fishkill
Water is the universal solvent • It doesn’t dissolve everything, but more than most other solvents • Why? • Water is a polar molecule • It has electrical properties • It is held together with covalent bonds Lets Talk about Water
Sharing Electrons • Covalent Bonds involve sharing electrons • But those electrons are not necessarily shared evenly • Oxygen hogs the electrons • Hydrogen is missing the ones O is hogging
Water is Polar • The water molecule has two ends, POLES • A + pole and a – pole • This polarity is why water does all the cool stuff it does • This polarity is why water can dissolve ionic compounds like salt, NaCl
Factors Effecting Solubility • Each solute dissolves differently • In the set of solubility curves to the right, what is the biggest factor that effects solubility? • Right! Solvent Temperature
What about Gases? • NH3 is a gas • Describe it’s solubility as the water temp changes. • See Figure 27 on page 62 in your book • What else effects the solubility of gases? How?
DO, Dissolved Oxygen is important • Oxygen gas gets dissolved in water • That is the oxygen the fish breathe • Aeration is the process by which air is mixed with water to dissolve oxygen and other gases
Heavy Metals • Metal ions exist in natural water sources • They get dissolved as water percolates through soil and bedrock in an aquifer • Some minerals (metal ions) are fine • Some can be deadly
Lead, Cadmium and Mercury • These elements are called heavy metals • They can all dissolve in water, and all cause health problems for human and other organisms • http://search.usatoday.com/search/search.aspx?qt=news%2Cyss%2Cweb%2Crel%2Cimg%2Ctop10%2Ckmatch&nr=5&s=sb&kw=mercury&goBtn2.x=13&goBtn2.y=9
Heavy metals can cause a variety of health problems • Organ damage: liver, kidney, heart • Central nervous system: motor control, brain function • Developmental problems: physical and intellectual Heavy metal Poisoning
Recently in Euclid Creek The Euclid Creek Watershed drains Richmond Hts, Lyndhurst, South Euclid, Cleveland Hts, University Hts, part of Cleveland and Euclid. Tributaries feed into Euclid Creek which flows directly into lake Erie WKYC, Channel 3 just did a story on a recent fishkill reported there www.wkyc.com Dissolved material Can Cause A Fishkill
Water will dissolve materials that are similar Water is polar and held together with covalent bonds Water will dissolve solutes that are polar Water will dissolve some ionic salts too Water will not dissolve materials that are non-polar Like Dissolves Like
Do not have any + or – characteristics There is nowhere for the polar water molecule to “grab” and “tear” the nonpolar molecule apart. Nonpolar molecules cannot be dissolved by water They can be dissolved by nonpolar solvents Styrofoam will dissolve in gasoline for example (under the supervision of an adult and outdoors) Nonpolar Solutes
Nonpolar Solutes Would be Visible • Nonpolar solutes do not dissolve • We should be able to catch them with a filter • Or skim them off the top
pH scale • The pH of the water in an ecosystem is important • The pH scale measures the acidity or alkalinity of solutions • The pH scale goes from 0 to 14
Changing PH • Most aquatic ecosystems’ pH is near 7, maybe a little higher • Aquatic ecosystems have chemical buffers that neutralize excess acids or bases and minimize pH change • However, events may occur which overwhelm that protection • A change in pH by 1 unit, is actually a power of 10. • If a stream’s pH goes from 7 to 5, it has become 102 or 100 times more acidic
Acid Rain creates other Problems • Acid precipitation can destroy food webs • Acid precipitation can interfere with development of larva and fish/amphibian eggs • Acid precipitation can dissolve heavy metal ions out of bedrock