Chapter 3Slide 2Water’s PolarityCohesion and AdhesionSlide 5Moderation of TemperatureInsulation of Bodies of Water by Floating IceThe Solvent of LifeSlide 9Dissociation of Water MoleculesThe pH ScaleSlide 12You should now be able to:PowerPoint Lectures for Biology, Eighth EditionNeil Campbell and Jane ReeceChapter 3Chapter 3Water and the Fitness of the EnvironmentWater’s Polarity•The polarity of water molecules–Allows them to form hydrogen bonds with each other–Contributes to the various properties water exhibits that makes it so suitable to supporting life.Hydrogenbonds++HH++ – – – –Figure 3.2Cohesion and Adhesion•Helps pull water up through the microscopic vessels of plantsWater-conductingcellsAdhesionCohesion150 µmDirectionof watermovement•Surface tension–Is a measure of how hard it is to break the surface of a liquid–Is related to cohesionFigure 3.4Moderation of Temperature•Water moderates air temperature–By absorbing heat from air that is warmer and releasing the stored heat to air that is coolerSan Diego 72°40 milesPacific Ocean70s (°F)80s90s100sSanta Barbara 73°Los Angeles (Airport) 75°Burbank90°San Bernardino100°Riverside 96°Santa Ana 84°Palm Springs106°Fig. 3-5•The hydrogen bonds in ice–Are more “ordered” than in liquid water, making ice less denseLiquid waterHydrogen bonds constantly break and re-formIceHydrogen bonds are stableHydrogen bondFigure 3.6Insulation of Bodies of Water by Floating IceNegative oxygen regions of polar water molecules are attracted to sodium cations (Na+).++++Cl –––––Na+Positive hydrogen regions of water molecules cling to chloride anions (Cl–).++++––––––Na+Cl–Figure 3.7The Solvent of Life•Water can also interact with polar molecules such as proteinsThis oxygen is attracted to a slight positive charge on the lysozyme molecule.This hydrogen is attracted to a slight negative charge on the lysozyme molecule.(a) Lysozyme molecule in a nonaqueous environment(b) Lysozyme molecule (purple) in an aqueous environment such as tears or saliva(c) Ionic and polar regions on the protein’s Surface attract water molecules. +–Figure 3.8–+Dissociation of Water MoleculesHHydroniumion (H3O+)HHydroxideion (OH–)HHHHHH+–+Figure on p. 52 of water dissociating H2O H+ + OH-waterHydrogen ionHydroxide ionSimplified Process•The pH scale (0-14) and pH values of various aqueous solutionsFig. 3-9Neutral solutionAcidic solutionBasic solutionOH–OH–OH–OH–OH–OH–OH–H+H+H+OH–H+H+H+H+OH–OH–OH–OH–H+OH–H+H+H+H+H+H+H+OH–Neutral [H+] = [OH–]Increasingly Acidic [H+] > [OH–] Increasingly Basic [H+] < [OH–] pH Scale012345678Battery acidGastric juice,lemon juiceVinegar, beer,wine, colaTomato juiceBlack coffeeRainwaterUrineSalivaPure waterHuman blood, tearsSeawater910Milk of magnesiaHousehold ammoniaHouseholdbleachOven cleaner11121314The pH Scale•Acid precipitation–Can damage life in Earth’s ecosystems01234567891011121314MoreacidicAcidrainNormalrainMorebasicFigure 3.10You should now be able to:1. List and explain the four properties of water that emerge as a result of its ability to form hydrogen bonds2. Distinguish between the following sets of terms: hydrophobic and hydrophilic substances; a solute, a solvent, and a solution, mole, molar concentration3. Define acid, base, and pH4. Explain how buffers workCopyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin
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