Post on 05-Apr-2018
7/31/2019 Ch.3 ppt AP
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Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings
PowerPoint Lectures forBiology, Seventh Edition
Neil Campbell and Jane Reece
Lectures by Chris Romero
Chapter 3
Water and the Fitness of
the Environment
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7/31/2019 Ch.3 ppt AP
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Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Concept 3.1: The polarity of water molecules results inhydrogen bonding
Polar
opposite ends of the molecule haveopposite charges
Polarity allows water molecules to form hydrogen
bonds with each other Oxygen is more electronegative
Animation: Water Structure
Hydrogenbonds
http://media/03_02WaterStructure_A.htmlhttp://media/03_02WaterStructure_A.html7/31/2019 Ch.3 ppt AP
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Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Concept 3.2: Four emergent properties of watercontribute to Earths fitness for life
Four of waters properties that facilitate anenvironment for life:
Cohesive behavior
Ability to moderate temperature
Expansion upon freezing
Versatility as a solvent
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Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Cohesion
Cohesionwhen water molecules bond to eachother by hydrogen bonds
helps the transport of water against gravity in
plantsAdhesion 2 different substances sticking together
Animation: Water Transport
http://media/03_03WaterTransport_A.htmlhttp://media/03_03WaterTransport_A.htmlhttp://media/03_03WaterTransport_A.html7/31/2019 Ch.3 ppt AP
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LE 3-3
Water-conducting cells
100 m
7/31/2019 Ch.3 ppt AP
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Surface tension is a measure of how hard it is tobreak the surface of a liquid
Surface tension is related to cohesion
7/31/2019 Ch.3 ppt AP
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7/31/2019 Ch.3 ppt AP
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Heat is absorbed when hydrogen bonds break
Heat is released when hydrogen bonds form
7/31/2019 Ch.3 ppt AP
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Moderation of Temperature
High Heat Capacity Water can absorb or release a large amount of
heat with only a slight change in its owntemperature
Heat is absorbed to break a hydrogen bond
Heat is released when a hydrogen bond is
formed
7/31/2019 Ch.3 ppt AP
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Heat and Temperature
Kinetic energy is the energy of motion Heat - totalamount of kinetic energy due to
molecular motion
Temperature - intensity of heat due to theaveragekinetic energy
7/31/2019 Ch.3 ppt AP
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Waters High Specific Heat
The specific heat of a substance:
is the amount of heat that must be absorbed orlost for 1 gram of that substance to change itstemperature by 1C
Example: boiling water in an iron pot
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Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Insulation of Bodies of Water by Floating Ice
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Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings
The Solvent of Life
A solution is a liquid that is a homogeneousmixture of substances
solvent
solute
An aqueous solution is one in which water is the
solvent
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LE 3-6
In water, ionic molecules are pulled apart by
the H2O They dissolve
In water, polar molecules do not dissolve, but
H2O is still attracted to the molecule (colloid)
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Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Hydrophilic and Hydrophobic Substances
A hydrophilic substance is one that has anaffinity for water
A hydrophobic substance is one that does nothave an affinity for water
It is non-polar
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Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Molecular mass = sum of all masses of all atomsin a molecule (Measured in Daltons)
Numbers of molecules are usually measured inmoles, with one mole being 6.02 x 1023 molecules
-Avogadros Number
Molarity is the number of moles of solute per liter
of solution
7/31/2019 Ch.3 ppt AP
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7/31/2019 Ch.3 ppt AP
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Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Concept 3.3: Dissociation of water molecules leads toacidic and basic conditions that affect living organisms
A hydrogen atom in a hydrogen bond between twowater molecules can shift from one to the other:
hydrogen atom is transferred as a proton, orhydrogen ion (H+)
The molecule with the extra proton is now ahydronium ion (H3O
+)
The molecule that lost the proton is now ahydroxide ion (OH-)
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Acids and Bases
acid increases the
H+ concentration
base reduces theH+ concentration
pH represents theH+ ions present
pH Scale01
2
3456789
1011121314 Oven cleaner
Household bleachHousehold ammoniaMilk of magnesia
Seawater
Pure waterHuman blood
UrineRainwaterBlack coffeeTomato juiceVinegar, beer, wine,colaDigestive (stomach)juice, lemon juice
Battery acid
Neutral[H+] = [OH]
IncreasinglyAcid
ic
[H+]>[OH]
IncreasinglyBasic
[H+]