Water, Acids

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Water, Acids BasesCh. 2-3
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Importance?

• 1. All chemical reactions that occur in living
  organisms occur in an aqueous environment.
  Example metabolic reactions
• 2. Temperature regulation. (homeostasis)

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Water is Unique

• Water is a polar molecule.Polarity
• What does having Polarity mean?
• 1. Allows water to be very effective in
  dissolving other substances. (sugar, saltetc.)

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• 2. Allows water molecules to stick to one
  another. How?
• -Hydrogen Bonds hold water molecules together.
• H-Bonds are weak and easily broken.

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• Polarity Hydrogen Bonding also allows Three
  Distinct Characteristics of Water
• 1. Cohesion- attraction of particles of the
  same kind. (surface tension)
• 2. Adhesion- attraction of particles of
  different kinds.

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• 3. Capillary Action- move against the pull of
  gravity. Example process of transpiration in
  plants.

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• Chemical Reactions and the Importance of Water
• Most chemical reactions in our body happen in
  aqueous solutions.
• -Water is the universal solvent.
• -Any substance dissolved in the solvent is the
• solute.
• -The concentration of a solution is the amount
• of solute dissolved in the solvent.
• -A saturated solution is one in which no more
• solute can dissolve.

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• Acids Bases in Living Organisms
• -Acidic solution contains more H3O ions
  (hydronium) than OH- ions (hydroxide).
• -Basic solution contains more OH- ions than H3O
  ions.
• -Buffers are naturally occurring substances in
  our bodies that help control acids and bases.

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• pH Scale
• -Acids and bases are measured using the pH scale.
• -The scale ranges from 0-14.
• 0-6 acidic
• 8-14 basic
• 7 neutral (water)