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Water & The Fitness Of The Environment

Water & The Fitness Of The Environment. Chapter 3. What molecule is a liquid at low temperatures (earth surface)?. Water: The Cradle of Life 2/3 of any organism’s body is water. All organisms require water to grow and reproduce. Tropical rain forests vs. a dry desert. Water.

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Water & The Fitness Of The Environment

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  1. Water & The Fitness Of The Environment Chapter 3

  2. What molecule is a liquid at low temperatures (earth surface)? Water: The Cradle of Life • 2/3 of any organism’s body is water. • All organisms require water to grow and reproduce. • Tropical rain forests vs. a dry desert

  3. Water • Water has a unique structure. • Most important chemical property of water-Hydrogen Bonding- weak chemical bonds with only 5-10 % of strength of covalent bonds. • Water is a polar molecule; with a δ– end and two δ+ ends. • Polarity of the molecule gives water its unique properties.

  4. H Water (H2O) O H  +  – Ammonia (NH3) N H H d+ + H Figure 2.15 Hydrogen Bonds • Forms when a hydrogen atom covalently bonded to one electronegative atom is also attracted to another electronegative atom  –  +  +

  5. Properties of Water • High Polarity- water is a good solvent for ions and polar compounds. • High Specific Heat- water can absorb a great deal of heat before changing temperature. • High Heat of Vaporization- many H-bonds must be broken before water can evaporate.

  6. Lower Density of Ice- water molecules in an ice crystal are further apart because of H- bonding. • Ioinization- water ionizes into H+ and OH- ions. • Cohesion- H-bonds hold water molecules together. • Adhesion- H-bonds between water and other polar compounds. • http://www.learner.org/resources/series61.html#

  7. Water Ionizes 2 H2O H3O+ + OH- Hydronium ion Hydroxide ion Or H2O H+ + OH- Hydrogen ion Hydroxide ion

  8. Definitions of Acids/Bases • pH = -log of [H+] • Neutral (pure water) = [H+] = [OH-]. • Acid = increases [H+], decreases [OH-], lower pH. • Bases = increases [OH-], decreases [H+], higher pH.

  9. Neutralization Reactions Acids + Bases Salts and Water HCl + KOH K+ + OH- + H+ + Cl- KCl + H2O

  10. Biological pH Buffers Buffers – substances that resist change in pH. In the blood (pH 7.4)…. Carbonic Anhydrase H20 + CO2H2CO3H+ + HCO3- (carbonic acid) (bicarbonate ion)

  11. Electrolytes - Other Blood Buffer Systems • KH2 PO4 K+ + H+ + HPO42- Monobasic potassium Phosphate • K2HPO4 2 K+ + HPO42- Dibasic Potassium Phosphate

  12. What is Acid Rain? H20 + SO2 + NOXH2SO4 + HNO3 Sulfuric Acid and Nitric Acid

  13. The Effects of Acid Rain Michelangelo’s Marcus Aurelius

  14. Limestone – A Natural Buffer Buffer – a solution that resists change in pH; either in water or soil; enzymatic buffers. H2SO4(aq) + CaCO3 H2CO3 + CaSO4

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