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Water is ESSENTIAL to life.
Living organisms are composed mostly of water.
• Humans – 76%• Jellyfish – 90%• Dried beans – 50%
• Is NOT 180 degrees
(H—O—H)
• IS a little more than
a 90 degree angle.
• Water is Polar – One end is positive, one end is negative.
The +/- attraction between the H (+) of one water molecule and the O (-) of the adjacent water molecule.
Oxygen is slightly negative
Hydrogen is slightly positive
Polarity & Hydrogen bonds http://videos.howstuffworks.com/hsw/19233-simply-science-atoms-sharing-electrons-video.htm
1. “Universal Solvent”2. Freezes & Floats3. Cohesion (Surface tension)4. Adhesion (Capillary action)5. High heat of vaporization6. High heat of fusion
SolutionA mixture of…
• Solute– A substance that is put INTO the solvent
to dissolve.
• Solvent– Substance that does dissolves the solute– Water - Universal Solvent
SUSPENSION
Ever hear…
Oil & water don’t mix???
Water dissolves polar (ionic) substances:
– SALT (NaCl)
Water dissolvesnon-polar molecules:
– O2Helps fish survive– CO2
Helps algae survive
BLOOD is 95% water. Ions (NaCl) dissolve in blood (SOLUTION).
Imagine if ice didn’t float on top of a lake…
Ice is dense less than water
Ice has spaces between its water molecules
Ice acts as an insulator to allow the water below to remain a liquid.
The water strider bug relies on surface tension to survive.
The hydrogen bonds pull a water molecule in every direction by adjacent molecules.
Water molecules at the surface are not pulled from above.
This produces a “tension”.
What substance “broke” the tension in the Water Lab?
COHESION – The attraction between water molecules make them “stick” together.
ADHESION – The attraction between a water molecule and another substance.
CAPILLARY – Any thin long tube.
CAPILLARY ACTION – DUE TO cohesion & adhesion Water acts like a magnet and pull itself up against gravity.
Living things have capillary tubes:• Animals - blood vessels• Plants – xylem/phloem
• From - roots• To - leaves
Which substance has greater ADHESIVE properties?
COHESION: Water “sticks” to water
ADHESION: Water “sticks” to another substance
MercuryRed dyed water
Compared to other liquids it takes a lot of energy to evaporate water.
(Less evaporation leaves more water available for living things)
• High heat of fusionLarge bodies of water change temperature more slowly than air does.
(Lakes/ponds stay warmer, longer for living things)