the extraordinary properties of water warm-up write the chemical formula for water. draw a water...

The Extraordinary The Extraordinary Properties of WaterProperties of Water

Warm-up

Write the chemical formula for water.

Draw a water molecule. Indicate its atoms and their charges.

The Water MoleculeThe Water Molecule

WaterWater•A water molecule (H2O) is

made up of threethree atoms - one oxygen and two hydrogens.

H

HO

Water is PolarWater is Polar• In each water molecule, the oxygen oxygen

atom atom has a very has a very strong attraction strong attraction (high affinity) for the electrons of the(high affinity) for the electrons of the hydrogens.hydrogens.

• The oxygenoxygen end “acts” negative.negative.• The hydrogenhydrogen end “acts” positive.positive.• This causes the water molecule to be

POLAR.POLAR.• AA polar molecule polar molecule is one that has an is one that has an

unequal distribution of unequal distribution of chargecharge..

Hydrogen Bonds Exist Hydrogen Bonds Exist Between Water MoleculesBetween Water Molecules

• Formed between a Formed between a highlyhighly electronegative electronegative atomatom of a polar of a polar molecule and a molecule and a hydrogenhydrogen of a different of a different moleculemolecule

• OneOne hydrogen bond is hydrogen bond is weakweak , but , but manymany hydrogen bonds are hydrogen bonds are strong.strong.

Interactions Between Interactions Between Water MoleculesWater Molecules

TheThe negative oxygen negative oxygen side of one water side of one water molecule is attracted to the molecule is attracted to the positive hydrogen positive hydrogen

side of another water molecule and forms a side of another water molecule and forms a HYDROGEN BOND.HYDROGEN BOND.

What are What are the the

PropertieProperties of s of

Water?Water?

Properties of WaterProperties of Water

•CohesionCohesion

Properties of WaterProperties of Water

•CohesionCohesion•AdhesionAdhesion

Properties of WaterProperties of Water

•CohesionCohesion•AdhesionAdhesion•High Specific HeatHigh Specific Heat

Properties of WaterProperties of Water

•CohesionCohesion•AdhesionAdhesion•High Specific HeatHigh Specific Heat•High Heat of High Heat of VaporizationVaporization

Properties of WaterProperties of Water

•CohesionCohesion•AdhesionAdhesion•High Specific HeatHigh Specific Heat•High Heat of VaporizationHigh Heat of Vaporization•Less Dense as a SolidLess Dense as a Solid

Properties of WaterProperties of Water

•CohesionCohesion•AdhesionAdhesion•High Specific HeatHigh Specific Heat•High Heat of VaporizationHigh Heat of Vaporization•Less Dense as a SolidLess Dense as a Solid•Universal SolventUniversal Solvent

Universal SolventUniversal SolventPolarity makes Water a good solvent•Solvent = a substance in which another substance is dissolved•Solute = the substance dissolved in a solvent•Solution = when a solvent and solute are combined

solvents dissolve solutes creating solutions

SolutionSolution• Ionic compounds disperse as Ionic compounds disperse as

ionsions in water (Salt = Na+ and in water (Salt = Na+ and Cl-)Cl-)

• Water molecules Water molecules then attach then attach to the to the ionsions dissolved in the dissolved in the solution.solution.

What dissolves in water?• Hydrophilic

– substances that have an attraction to H2O– polar or non-polar?

Honors Biology

What doesn’t dissolve in water?• Hydrophobic

– substances that don’t have an attraction to H2O

– polar or non-polar?

fat (triglycerol)

Oh, lookhydrocarbons!

Honors Biology

CohesionCohesion• AttractionAttraction between molecules of between molecules of

the the same substance same substance (why water (why water is attracted to itself).is attracted to itself).

• Results in Results in surface tensionsurface tension (a (a measure of the strength of measure of the strength of water’s surface).water’s surface).

• Produces a Produces a surface film surface film on water on water that that allows insects to walk on allows insects to walk on the surfacethe surface of water. of water.

Cohesion …Cohesion …

Helps insects walk across water

AdhesionAdhesion• Attraction between two Attraction between two differentdifferent

substancessubstances..• Water will make Water will make hydrogen bonds with hydrogen bonds with

other surfacesother surfaces such as glass, soil, plant such as glass, soil, plant tissues, and cotton. tissues, and cotton.

• CapillaryCapillary actionaction-water molecules will “tow” -water molecules will “tow” each other along when in a thin glass tube.each other along when in a thin glass tube.

• Example: Example: transpirationtranspiration - process in which - process in which water evaporates from water evaporates from plant leavesplant leaves. Water . Water is simultaneously drawn up through is simultaneously drawn up through rootsroots from surrounding soil and delivered to rest from surrounding soil and delivered to rest of plant through of plant through veinsveins..

Adhesion Causes Adhesion Causes Capillary ActionCapillary Action

Gives water the ability to “climb”

structures

Adhesion Also Causes Adhesion Also Causes Water to …Water to …

Form spheres & hold onto

plant leaves

Attach to a spider web

High Specific HeatHigh Specific Heat• Amount of Amount of heatheat needed to raise or needed to raise or

lower lower 1g1g of a substance of a substance 1° C1° C..

• Water resists temperature Water resists temperature changechange, , both for heating and cooling.both for heating and cooling.

• Water can absorb or release large Water can absorb or release large amounts of heat energy with little amounts of heat energy with little change in actual temperature.change in actual temperature.

High Heat of High Heat of VaporizationVaporization

• Amount of energy to convert 1g of Amount of energy to convert 1g of a substance from a a substance from a liquid to a gasliquid to a gas

• In order for water to evaporate, In order for water to evaporate, hydrogen hydrogen bonds must be bonds must be brokenbroken..

• As water evaporatesAs water evaporates, it removes a , it removes a lot of lot of heatheat with it. with it.

High Heat of High Heat of VaporizationVaporization

• Water's heat of vaporization is 540 cal/g.540 cal/g.

• In order for water to In order for water to evaporateevaporate, , each gram must each gram must GAIN 540 GAIN 540 calories (temperature doesn’t calories (temperature doesn’t change --- 100change --- 100ooC).C).

• As water evaporatesAs water evaporates, it removes , it removes a lot of a lot of heatheat with it with it (cooling (cooling effect)effect)..

• Water vapor Water vapor forms a kind of global ‘‘blanket” which helps to keep the earth warm.

• Heat radiates from the sun. Heat radiates from the sun. The surface of the earth is warmed as heat is

Absorbed Absorbed by water by water vapor in thevapor in the atmosphere atmosphere.

Water is Less Dense in Water is Less Dense in Solid form.Solid form.

• Ice is Ice is less denseless dense as a solid than as a liquid (ice floats).

• Liquid water has hydrogen bonds hydrogen bonds that are constantly being constantly being brokenbroken and and reformed.reformed.

• Frozen Frozen water water forms a crystalcrystal-like-like latticelattice whereby molecules are set at fixed distances due to their H-bonds.

Water is Less Dense as Water is Less Dense as a Solida Solid

•Which is ice and which is Which is ice and which is water?water?

Water is Less Dense as a Water is Less Dense as a SolidSolid

WaterWater IceIce

HomeostasisHomeostasis• The ability to maintain a The ability to maintain a steady state steady state

despite changing conditions.despite changing conditions.• Water is important to this process Water is important to this process

because:because:a. It acts as a a. It acts as a good insulatorgood insulatorb. Resists temperature changeb. Resists temperature changec. c. Universal solventUniversal solventd. Coolantd. Coolante. Ice protects against temperature e. Ice protects against temperature

extremes ( extremes (insulatesinsulates frozen frozen lakes)lakes)

http://www.brainpop.com/science/earthsystem/water/

http://www.bozemanscience.com/water-life