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The Extraordinary The Extraordinary Properties of WaterProperties of Water
WaterWater
•A water molecule (H2O), is made up of three atoms: one oxygen and two hydrogen.
H
HO
Hydrogen BondsHydrogen Bonds
Formed between negative end of Formed between negative end of an atom of a polar molecule and a an atom of a polar molecule and a Hydrogen of another molecule Hydrogen of another molecule
Example: water molecules Example: water molecules
one hydrogen bond is weak , but one hydrogen bond is weak , but many hydrogen bonds are strongmany hydrogen bonds are strong
Properties of WaterProperties of Water
•At sea level, pure water boils at At sea level, pure water boils at 100 °C and freezes at 0 °C.100 °C and freezes at 0 °C.
•The boiling temperature of The boiling temperature of water decreases at higher water decreases at higher elevations (lower atmospheric elevations (lower atmospheric pressure). pressure).
•For this reason, an egg will For this reason, an egg will take longer to boil at higher take longer to boil at higher altitudesaltitudes.
Properties of WaterProperties of Water
•What are they?What are they?
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 High Heat of VaporizationVaporization
•Less Dense as a SolidLess Dense as a Solid
CohesionCohesion•Attraction between particles of Attraction between particles of the the same substancesame substance
- why water is attracted to why water is attracted to itselfitself
Results in:Results in:Surface tensionSurface tension (a measure of (a measure of the strength of water’s surface) the strength of water’s surface)
•surface filmsurface film on water on water -allows insects to walk on the -allows insects to walk on the
surface of water surface of water
AdhesionAdhesion•Attraction between two Attraction between two different different substances. substances.
- water will make hydrogen - water will make hydrogen bonds with other surfaces such as bonds with other surfaces such as glass, soil, plant tissues, and cotton. glass, soil, plant tissues, and cotton.
•CapillaryCapillary actionaction-water molecules -water molecules will “tow” each other along when in will “tow” each other along when in a thin glass tube.a thin glass tube.
Example: transpiration process Example: transpiration process which plants and trees remove which plants and trees remove water from the soil, and paper water from the soil, and paper towels soak up water.towels soak up water.
.
High Specific HeatHigh Specific Heat
Amount of heat needed to raise Amount of heat needed to raise or lower 1g of a substance 1° C.or lower 1g of a substance 1° C.
•Water Water resistsresists temperature temperature change, both for heating and change, both for heating and cooling.cooling.•Example: Lake or pond heating Example: Lake or pond heating and cooling during the seasonsand cooling during the seasons
High Heat of High Heat of VaporizationVaporization
Amount of energy to convert Amount of energy to convert 1g or a substance from a liquid 1g or a substance from a liquid to a gasto a gas
• In order for water to In order for water to evaporate, hydrogen bonds evaporate, hydrogen bonds must be broken. As water must be broken. As water evaporates, it removes a lot of evaporates, it removes a lot of heat with it.heat with it.
•Water vapor forms a kind of global ‘blanket’ which helps to keep the earth warm.
•Heat radiated from the sun-warmed surface
of the earth is absorbed and held by the vapor.”
Water is Less Dense as Water is Less Dense as a Solida Solid
•Ice is less dense as a solid than as a liquid (ice floats)Liquid water has hydrogen bonds that are constantly being broken and reformed.Frozen water forms a crystal-like lattice whereby molecules are set at fixed distances.
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•Ability to maintain a steady state Ability to maintain a steady state
despite changing conditionsdespite changing conditions•Water is important to this process Water is important to this process
because:because:a. Makes a a. Makes a good insulatorgood insulatorb. Resists temperature changeb. Resists temperature changec. c. Universal solventUniversal solventd. Coolantd. Coolante. Ice protects against e. Ice protects against temperature extremestemperature extremes
