1.%20The%20polarity%20of%20water%20molecules%20results%20from%20hydrogen%20bonding

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1. The polarity of water molecules results from
hydrogen bonding
CHAPTER 3WATER AND THE FITNESS OF THE ENVIRONMENT

• Water molecule- two hydrogen atoms form
  ____________________ bonds with an oxygen atom.
• Partial negative charge
• Partial positive charge

_____- because each share one electron ______-
because O is more electronegative than
H ________- because they each share electrons
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• Water has unusual properties because of
  attractions between ______ molecules.
• The slightly negative regions interact with
  slightly positive regions of nearby molecules,
  forming a _________________.
• Each water molecule can form hydrogen bonds
  with up to ________ neighbors.

Fig. 3.2
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Properties of water

• 1. _________- Hydrogen bonds hold water together.

Why? ______________
Water pulled up to tree tops
2. High ______________
an invisible film
Why? _____________
3. _____________ air temperatures
Why? _____________

• Water resists changes in temperature

• Freezes at __ C and boils at ____ C

• As a liquid evaporates, the surface of the
  liquid that remains behind cools -
  ______________________.

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4. Ice is about ________ dense than water at 4oC,
thus ice ______
Thus, oceans and lakes dont freeze solid
5. Water is the solvent of life
Why? It forms _____________________ with many
molecules
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How do measure amounts? Answer- In ______

• A _________ molecular weight (in grams)
• Example - sucrose (C12H22O11)
• A carbon atom weighs 12 daltons, hydrogen 1
  dalton, and oxygen 16 daltons.
• The _________________ of sucrose is 342 D.
• (12 x 12D) (22 x 1D) (11 x 16D)
• Thus, one mole of sucrose weighs 342 g

• of molecules in a mole _______________ 6.02
  x 1023.
• 1 mole ethyl alcohol (C2H6O) 46g (also contains
  ___________________

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• How do we measure acidity?
• Answer ___________.

• A water molecule dissociates into a hydrogen ion
  and a hydroxide ion
• H2O ltgt H OH-
• At equilibrium the concentration of H or OH- is
  10-7M (25C) .

• Hydrogen and hydroxide ions are very reactive,
  and thus drastically affect the proteins and
  other molecules of a cell.

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• The _________ of their __ and ____ concentrations
  is constant at _______.
• H OH- 10-14
• In a neutral solution, H ___M and OH-
  ____ M
• If add acid, H ions increase and OH- ions
  decrease.

• The H and OH- concentrations of solutions can
  vary by a factor of 100 trillion or more.
• The H and OH- concentrations are typically
  expressed via the ___________.
• The pH scale, ranging from ________, compresses
  the range of concentrations by employing
  ___________.
• pH - log H or H 10-pH

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• In a neutral solution H ___M, and the pH
  __.
• Values for pH decline as H _______.
• Most biological fluids have pH values in the
  range of ______.
• Each pH unit represents a ________ difference in
  H and OH- concentrations.

Fig. 3.8