03-2010C-10 - Water and the Fitness of the Environment...

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Unformatted text preview: Water and the Fitness of the Environment Chapter 3 Chapter 3 Page 1 : Properties of Water s Water molecules are polar and hydrogen bond to Water each other. This bonding is responsible for the special properties of water special s The properties of water are as follows: s Cohesion = water molecules stick together as a result of the partial charge attractions between the hydrogen and oxygen. This is one reason plants can transport water against gravity. Chapter 3 Page 2 : Properties of Water Cont. s Adhesion = clinging of one substance to another. In plants the water molecules cling to the sides of the vessels helping transport against gravity. This is also seen in glass graduated cylinders in the lab Ex meniscus graduated s Surface tension = level of difficulty involved in breaking or stretching the surface of a liquid stretching s High specific heat = this means how successfully a substance resists changing temperature substance What Is Specific Heat??????? Again s The amount of amount of heat that must be The gained or lost to change the temperature of 1 gram of a substance by 1° C. gram s Water absorbs a lot of heat before its temp rises s Why???????? Surface Tension is holding me up! Chapter 3 Page 4: Properties of Water Cont. s High heat of vaporization = it takes a great amount of energy to convert water from liquid to gas. This helps moderate earth’s climate in the case of water. case s Water expands when it freezes; it becomes less it dense and floats dense s Water is a solvent; many substances dissolve in it Chapter 3 Page 5 : Acids and Bases s Hydrophobic = repelled by water; mostly non polar substances substances s Hydrophilic = water loving or attracted to water. Most of these compounds are polar or charged. these s Acid = substance which increases the H ion in a solution s Base = substance which accepts H ions or donates OH. Bases reduce the H ion concentration of a solution. Bases pH s pH = negative log of the H ion concentration. pH declines as H ion concentration increases and increases as H ion concentration decreases and The Formulas: pH = - log [H+] s pOH = - log [OH-] pOH s Chapter 3 Page 6 : Acids and Bases Cont. s pH scale is logarithmic. This means for every unit of pH increase or decrease, the ion concentrations change by a factor of 10 s the pH scale runs from 0 -14. Seven is neutral. Less than the seven is acid and greater than seven is base seven s you can use the concentration acid or base to determine the corresponding concentration because [H] x [OH] = 14 14 Chapter 3 page 7 : Acids and Bases Cont. s Buffers are substances that minimize chances is the H ion or OH ion concentration or s Ex Human Blood pH range 7.35 -7.45 optimum humans Ex can only survive blood pH of 7 or greater than 7.8 for a few minutes few s Buffers work by accepting excess H ions and donating H Buffers ions when depleted. It can in practice also occur with donation of OH we won’t get into that here Buffers are extremely essential in biological systems Buffers s Chapter 3 Page 8: Acid Rain s Normal rain pH = about 5.6 s Acid rain = any pH below that s Ecological damage of great proportions is occurring in Ecological Europe and in some of our high altitude systems. Europe Acidification of seawater and coral reefs s Reduction in carbonate ions in seawater s Study by Langdon indicates coral reef calcification decreased bt acidification What is the pH of a liquid that has a [H] of 0.0001 A. B. C. 1 4 3 Problem Solving: s What is the [ H+ ] of an acid that is pH 5? of s What is the pH of a substance with an What [OH-] of 0.0000001? [OH s The pH in your fish bowl was 12 yesterday. The You put in acidifier and measure the pH + today. It is now 8. What is the H difference? today. ...
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