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Chapter 3: Chapter 3: WaterWater
Water’s PolarityWater’s PolarityCohesion, moderation of Cohesion, moderation of
temperature, ice is less dense, temperature, ice is less dense, universal solventuniversal solvent
Dissociation of water Dissociation of water moleculesmolecules
pHpH
T.O.D:(table from old study guide)take home essay?
T.O.D:(table from old study guide)take home essay?
WATER:WATER: the stuff of the stuff of life!life!
www.pascochamber.org/ visitorInfo.htmwww.pascochamber.org/ visitorInfo.htm
www.hd.org/Damon/photos/natural-science/&h=254&w=243&prev=/images
Water’s Water’s polarity polarity and and hydrogen hydrogen bondsbonds
Account for its unique properties that Account for its unique properties that contribute to the fitness of Earth’s as contribute to the fitness of Earth’s as an environment for life.an environment for life.
Cohesion/AdhesionCohesion/Adhesion
Cohesion is water’s attraction to Cohesion is water’s attraction to waterwater
Adhesion is water’s attraction to Adhesion is water’s attraction to other substancesother substances
Surface tensionSurface tension Water transport in plants, up ___ Water transport in plants, up ___
tubestubes
Stabilize temperaturesStabilize temperatures
WHY?WHY? High specific heatHigh specific heat Water moderates global and Water moderates global and
organismal temperaturesorganismal temperatures Evaporative cooling is important Evaporative cooling is important
for animals as well as plantsfor animals as well as plants
Expansion Expansion upon freezingupon freezing
Because of Hydrogen bonding …Because of Hydrogen bonding … 00° C ° C Ice is less dense than liquid Ice is less dense than liquid
waterwater When is water most dense?When is water most dense?
If this didn’t happen, bodies of water If this didn’t happen, bodies of water would freeze solidwould freeze solid
Structure of Ice vs liquid Structure of Ice vs liquid waterwater
VersatileVersatileSolvent:Solvent:
Ex: Salt and Ex: Salt and waterwater
Ionic and Ionic and polar com-polar com-pounds pounds dissolve in dissolve in waterwater
Even very large Even very large molecules like molecules like proteins proteins dissolve in dissolve in water as long water as long as there are as there are areas of ionic or areas of ionic or polar bonds.polar bonds.
The pH scaleThe pH scale pH=The measure of pH=The measure of
HH++ and OH and OH-- in a in a solution.solution.
Scale 0-14…Scale 0-14… Acids=increase the Acids=increase the
HH++ concentration concentration Bases=reduce the Bases=reduce the
HH++ concentration concentration
pH = -log[HpH = -log[H++]] Neutral = 10Neutral = 10--
77[H+][H+]
Ex:Ex: pH 9 pH 9 has H has H++ concentration of concentration of 1010-9-9 M and an OH M and an OH-- concentration of concentration of 1010-5 -5 MM
Practice problems…Practice problems…
BuffersBuffers Acid rainAcid rain
Ch.1-4 Quiz study tips:Ch.1-4 Quiz study tips:
Practice questions at the end of Practice questions at the end of the chaptersthe chapters
The test’s CD ROM demonstrations The test’s CD ROM demonstrations and practice questionsand practice questions
Study your HW notes and class Study your HW notes and class notesnotes
SourcesSources
Campbell, Reece, Mitchell. Campbell, Reece, Mitchell. Biology, 5Biology, 5thth Ed. 1999, Chap- Ed. 1999, Chap-ter one. Pgs. 1-21.ter one. Pgs. 1-21.
Campbell, Reece, Mitchell. Campbell, Reece, Mitchell. Biology, 5Biology, 5thth Ed. 1999, Ed. 1999, Presentations CD-ROM.Presentations CD-ROM.
Click art CD-ROM, Click art CD-ROM, Broderbund.Broderbund.
core.federated.com/ ~jim/water.jpgcore.federated.com/ ~jim/water.jpg
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