Properties of water lesson


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Properties of water lesson

  1. 1. 1. Cohesion & adhesion2. Low density solid3. Solubility: a good solvent4. High specific heat capacity5. High heat of vaporization & fusion6. Ionization: determines pH
  2. 2.  Cohesion:  the clinging of a substance to itself  hydrogen bonds between water molecules holding water together Adhesion:  the clinging of one substance to another  E.g. Meniscus: hydrogen bonds between water molecules and the glass of a test tube
  3. 3.  A measure of how difficult it is to break the surface of a liquid Surface tension is one of the results of cohesion in water Video: A National Geographic video showing how a lizard employs the
  4. 4.  Water is most dense at 4oC Ice is less dense than water Water is the only type of matter which becomes less dense when a solid
  5. 5. Aquatic life When the temperature of the atmosphere falls below 0oC, the water at the surface gradually freezes to ice The water under the ice remains at 4oC
  6. 6.  Amount of heat energy needed to increase the temperature of a substance by 1oC Water has a high specific heat capacity:  Water is capable of absorbing a lot of heat without increasing in temperature  Demonstration: water balloon
  7. 7.  Help organisms maintain constant body temperature Large bodies of water have moderating effect on nearby land temperature
  8. 8.  Heat of vaporization: amount of heat a liquid must absorb to be converted to a gas Heat of fusion: amount of heat a solid must absorb to be converted to a liquid Water has high heat of both vaporization and fusion Relevance: sweat
  9. 9.  Hydration shell Some biologically significant solutes include salts, sugars, proteins, vitamins
  10. 10. Hydration Shells
  11. 11.  Many molecules are able to dissolve in water. Organic matter may be hydrophilic or hydrophobic.
  12. 12.  H2O  H+ + OH- Reversible pH = -log[H+] Relevance: Organisms are very sensitive to pH changes
  13. 13. Is water an acid or a base? H 2O + H 2O H3O+ + OH-
  14. 14. Is water an acid or a base? conjugate base acid H 2O + H 2O H3O+ + OH- acid conjugate base
  15. 15.  Acid  compounds that will donate a proton in solution  results in a negative charge Base  compounds that will receive a proton in solution  results in a positive charge