Water

STUDY PLAN The Water Molecule The Water Molecule Water unusual Thermal Characteristics Water unusual Thermal Characteristics Water is a Powerful Solvent Water is a Powerful Solvent Gases dissolve in Seawater Gases dissolve in Seawater Acid-Base Balance Acid-Base Balance The Ocean is Stratified by Density The Ocean is Stratified by Density

STUDY PLAN Light does not travel far through the Ocean Light does not travel far through the Ocean Sound travels much farther than light in the ocean Sound travels much farther than light in the ocean The Water Cycle The Water Cycle

The Water Molecule What is a molecule? What is a molecule? Chemical bonds Chemical bonds Polar covalent Polar covalent Adhesion vs. Cohesion Adhesion vs. Cohesion Hydrogen Bonds Hydrogen Bonds

 One atom of oxygen  Two atoms of hydrogen o - HH ++ Water Chemical Properties

Water unusual Thermal Characteristics Heat is not Temperature!!! Heat is not Temperature!!! Heat = energy (measured in joules or calories) Heat = energy (measured in joules or calories) Temperature is how rapidly the molecules move (measured in degrees) Temperature is how rapidly the molecules move (measured in degrees) 1 degree Celcius = 1.8 degrees Fahrenheit 1 degree Celcius = 1.8 degrees Fahrenheit

Not all substances have the same Heat Capacity Heat capacity = measure of heat required to raise the temperature of 1 gram of a substance by 1 degrees Celcius Heat capacity = measure of heat required to raise the temperature of 1 gram of a substance by 1 degrees Celcius 1 calorie = amount of heat required to raise 1 gram of water by 1 degree Celcius 1 calorie = amount of heat required to raise 1 gram of water by 1 degree Celcius

Water’s Temperature Affects its Density Density = mass/volume Density = mass/volume

Phases of Matter

Phases of matter - solids Definite shape and volume Definite shape and volume Rigid 3-D structure Rigid 3-D structure Atoms/molecules bonded in place Atoms/molecules bonded in place Allowed motions restricted to vibration in place only Allowed motions restricted to vibration in place only

Phases of matter - liquids Definite volume, indefinite shape Definite volume, indefinite shape Only weak cohesive bonds between component molecules Only weak cohesive bonds between component molecules Constituent molecules mostly in contact Constituent molecules mostly in contact Allowed motions Allowed motions – Vibration – Rotation – Limited translation

Phases of matter - gases Indefinite volume and shape Indefinite volume and shape Molecules mostly not in contact Molecules mostly not in contact Allowed motions Allowed motions – Vibration and rotation (molecules with more than one atom) – Translation on random, mostly free paths

Water becomes less dense when it Freezes Angle increases when water reaches the FREEZING POINT Angle increases when water reaches the FREEZING POINT –105 degrees  109 degrees Water expands 9% Water expands 9%

Water is a Powerful Solvent Water will dissolve anything Water will dissolve anything Polar nature Polar nature Ions Ions

Salinity = TDS Ocean water: % Ocean water: % 5,000 trillion kg of salt 5,000 trillion kg of salt If evaporation occurred -  45 m (150 ft) thick cover of salt If evaporation occurred -  45 m (150 ft) thick cover of salt Most abundant ions in water: Na and Cl Most abundant ions in water: Na and Cl

Gases dissolve in Seawater Cold vs. Warm seawater Cold vs. Warm seawater Nitrogen: 48% Nitrogen: 48% Oxygen: 36% Oxygen: 36% Carbon dioxide: 15% Carbon dioxide: 15% What happens to carbon dioxide in seawater? What happens to carbon dioxide in seawater?

Acid-Base Balance Measured with the pH scale Measured with the pH scale Acid vs. Base (alkaline) Acid vs. Base (alkaline) Ocean water is 7.8 Ocean water is 7.8

Density stratification of ocean water Warm water is less dense than cold water Warm water is less dense than cold water 3 density zones: 3 density zones: –Surface zone (mixed layer) –Pycnocline: 18% of all ocean water –Deep zone: 80% of all ocean water; below 1,000 m below 1,000 m –Thermocline: boundary between warm and cold water

Light does not travel deep What is light? What is light? Scattering Scattering Photic zone: top 600 m Photic zone: top 600 m Aphotic zone Aphotic zone Water transmits BLUE LIGHT more efficiently than RED: 71% of red will be absorbed at the top of the ocean Water transmits BLUE LIGHT more efficiently than RED: 71% of red will be absorbed at the top of the ocean

Sound travels deeper Speed of sound in seawater: 1500 m/sec. Speed of sound in seawater: 1500 m/sec. What is sonar? What is sonar? SOund Navigation And Ranging SOund Navigation And Ranging

Evaporation The vapor rises Condensation The Clouds form Precipitation The rain falls Transpiration The movement through plants