Water and Aqueous Systems

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Water and Aqueous Systems

• Chemistry
• Mrs. Coyle

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The Water Molecule

• Bent
• Two lone electron pairs
• Polar molecule

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Hydrogen Bonding

• The intermolecular forces in which hydrogen
  that is covalently bonded to a very
  electronegative atom is also weakly bonded to an
  unshared electron pair of another atom
  (N, O, F).

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• Hydrogen bonding is responsible for many of the
  unique properties of water such as
• high surface tension
• having a low vapor pressure
• having a lower density in the solid form than in
  the liquid form.

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• Surface tension causes water to form nearly
  spherical droplets.

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http//www.chemistryland.com/CHM107/Water/WaterBea
dsOnPlantPlusWaterCharge.jpg
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Surface Tension

• Surface tension is an inward force that causes
  the surface to behave as a skin.
• The higher the intermolecular forces the greater
  the surface tension.

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Surface Tension of Water
http//quest.nasa.gov/space/teachers/microgravity/
image/66.gif
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Water Mercury
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Surfactants

• Substances that interfere with the hydrogen
  bonding between molecules and reduce the surface
  tension.
• Cause spreading or wetting.
• Examples of surfactants are soaps.

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Waters Low Vapor Pressure

• Because of the hydrogen bonds holding the water
  molecules together, the molecules have a low
  tendency to break free from the surface into the
  vapor phase.

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Water has a relatively high boiling point.

• Why?

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Density of Water

• Ice has a lower density than liquid water.
• Maximum density of water happens at 4OC.

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Density of Water
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Ice- (Honeycomb Shape)