The Chemistry of Water

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The Chemistry of Water
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Water is a polar molecule.Has both
charges

• The Chemistry of Water

H bond
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1. When water molecules form hydrogen bonds with
other water molecules.

• Cohesion

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• Adhesion

• H2O molecules form hydrogen bonds with other
  polar molecules.

• water climbs up fiber ex. paper towel

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• Surface tension
• Adhesion Cohesion working together

• A property of liquid surfaces that causes the
  surface layer to behave like a thin elastic
  'skin results in a downward pulling motion of
  water molecules.

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• Capillary Action
• Adhesion Cohesion working together

The upward pull of water against gravity from
plants roots to the leaves.
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1. H2O molecules form hydrogen bonds with each
other2. attracted to 3. creates a sticky
molecule

• The Chemistry of Water

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Low Density of Ice

• Most (all?) substances are more dense when they
  are solid
• But not water
• Ice floats!
• H bonds form a crystal
• with loose structure

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Ice floats..
ice floats because hydrogen bonds hold water
molecules further apart in a solid than in a
liquid
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Why is it so impt that ice floats?

• Oceans lakes dont freeze solid
• if ice sank
• eventually all ponds, lakes even ocean would
  freeze solid
• during summer, only upper few inches would thaw
• surface ice insulates water below
• allowing life to survive the winter

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• Temperature Moderation

• Organisms relay on heat of vaporization to remove
  heat

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Temperature Moderation

• H2O resists changes in temperature
• takes a lot to heat it up
• takes a lot to cool it down
• H2O moderates temperatures on Earth

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• The Universal Solvent

• H2O is a good solvent due to its polarity
• polar H2O molecules surround ions
• solvents dissolve solutes creating aqueous
  solutions
• Saltwater which is solute?
• which is solvent?

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• The universal solvent

Many other unique properties of water are due to
the hydrogen bonds. For example, ice floats
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• Questions

• What causes hydrogen bonds to form between polar
  molecules?
• (A) The atoms of polar molecules give up
  electrons to hydrogen atoms.
• (B) Polar molecules have partially charged
  regions that attract other polar molecules. 
• (C) The hydrogen atom in water molecules becomes
  negatively charged. 
• (D) Hydrogen atoms in water molecules attract
  each other with positive charges.

Many other unique properties of water are due to
the hydrogen bonds. For example, ice floats
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• Questions

2. Which of the following properties of water is
not caused by hydrogen bonding?  (A) pH  (B) cohes
ion  (C) adhesion  (D) surface tension
Many other unique properties of water are due to
the hydrogen bonds. For example, ice floats
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• Questions

3. What term describes the sugar in a glass of
lemonade?  (A) solvent  (B) solution  (C) solute 
(D) protein
Many other unique properties of water are due to
the hydrogen bonds. For example, ice floats
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• Questions

4. What is the relationship between hydrogen
bonds and ionic bonds? 5. What determines
whether a compound will dissolve in water? 6.
How do polar molecules form hydrogen bonds?
Many other unique properties of water are due to
the hydrogen bonds. For example, ice floats
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Properties of Water Review

• Ability to dissolve other substances
• Creates surface tension
• Exhibits capillary action
• Low density of ice
• Temperature moderation
• Goldfish hibernate at the bottom of a pond in the
  winter.
• Humans cannot have too high of a fever or the
  chemical reactions in their bodies will stop.
• Land near large bodies of water stay warmer
  longer in the fall then land away from large
  bodies of water.

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Properties of Water Review

• Goldfish hibernate at the bottom of a pond in the
  winter.
• Humans cannot have too high of a fever or the
  chemical reactions in their bodies will stop.
• Land near large bodies of water stay warmer
  longer in the fall then land away from large
  bodies of water.