Water

695 views

Published on

Published in: Technology, Business
  • Be the first to comment

Water

  1. 1. Water The Molecule That Supports All Of LifeAP Biology 2007-2008
  2. 2. The Chemistry Of Water  Water is a polar molecule  The atoms of water are held together by polar covalent bonds  Who wins?  Oxygen(-)?  Hydrogen(+)?AP Biology
  3. 3. Noodle time! Do hydrogen bonds hold oxygen and hydrogen together IN water? Pink – Yes Purple – No Yellow – I’m not sureAP Biology
  4. 4. Noodle time! What kind of bonds do hold the hydrogen atoms to the oxygen atom in H2O? Pink – Non-polar covalent Purple – Hydrogen Yellow – Ionic Green – CovalentAP Biology
  5. 5. The Chemistry Of Water  Molecules of water are held together by Hydrogen bonds  H+ of one water molecule attracted to O- of another water moleculeAP Biology
  6. 6. The Properties Of Water (Super Powers) 1. Cohesion & Adhesion 2. Good Solvent 3. Low Density As A Solid 4. High Specific Heat I’m pretty super! 5. Heat Of Vaporization 6. Ionization of WaterAP Biology
  7. 7. 1.Cohesion  Caused by the hydrogen bonds between H2O molecules  Makes water “sticky”  Allows for this kid to drink out of his straw Try that with flour…  And this guy to walk on water or sugar…AP Biology
  8. 8. 1. Adhesion  Caused by hydrogen bonding between H20 and OTHER molecules  Causes meniscusAP Biology
  9. 9. Penny ChallengeAP Biology
  10. 10. TranspirationWater defies gravity and travels through plants fromthe roots up. Caused by COHESION & ADHESION!AP Biology
  11. 11. 2. Universal Solvent  Solvents dissolve solutes creating solutions  The polarity of H20 makes it a good solvent  polar H2O molecules surround + & – ions pulling them apartAP Biology
  12. 12. Noodle Time  Is any kind of liquid a good solvent?  Let’s try it!AP Biology
  13. 13. What dissolves in water?  Hydrophilic  substances have attraction to H 2O  polar or non-polar?AP Biology
  14. 14. What doesn’t dissolve in water?  Hydrophobic  substances that don’t have an attraction to H2O  polar or non-polar?AP Biology fat (triglycerol)
  15. 15. 3. Low Density as a solid (Ice Ice Baby)  Most substances are more dense when they are solid, but not water…  Ice floats!  H bonds form a crystal And this has made all the difference!AP Biology
  16. 16. Water vs Ice – Use the Water KitsAP Biology
  17. 17. Why is “ice floats” important?  Oceans & lakes don’t freeze solid  surface ice insulates water below  allowing life to survive the winter  if ice sank…  ponds, lakes & even oceans would freeze solid  in summer, only upper few inches would thaw  seasonal turnover of lakes  sinking cold H2O cycles nutrients in autumnAP Biology
  18. 18. The Fireproof Balloon  NOODLE TIME! What will explode first? Pink - A balloon with H2O Green - A balloon without H2O Why did this happen?AP Biology
  19. 19. 4. High Specific Heat  H2O resists changes in temperature  high specific heat  takes a lot to heat it up  takes a lot to cool it down  H2O moderates temperatures on EarthAP Biology
  20. 20. Evaporative cooling 5. Heat of vaporization Organisms rely on heat of vaporization to remove body heatAP Biology
  21. 21. Alcohol vs. Water  IN YO’ BODIES!AP Biology
  22. 22. 6. Ionization of water & pH  Water ionizes H2O → H+ + OH–  H+ splits off from H2O, leaving OH–  if [H+] = [-OH], solution is neutral  if [H+] > [-OH], solution is acidic  if [H+] < [-OH], solution is basic  pH scale  how acidic or basic a solution is  1 → 7 → 14AP Biology
  23. 23. H+ Ion Examples of Solutions Concentration pH pH Scale 100 10–1 0 1 Hydrochloric acid Stomach acid, Lemon juicetenfold change 10–2 2 in H+ ions 10–3 3 Vinegar, cola, beer 10–4 4 Tomatoes pH1 → pH2 10–5 5 Black coffee, Rainwater 10-1 → 10-2 10–6 6 Urine, Saliva 10 times less H + Pure water, Blood 10–7 7 pH8 → pH7 10–8 8 Seawater 10-8 → 10-7 10–9 9 Baking soda10 times more H+ 10–10 Great Salt Lake 10 pH10 → pH8 10–11 11 Household ammonia 10-10 → 10-8 10–12 12 Household bleach100 times more H+ 10–13 13 Oven cleaner 10–14 14 Sodium hydroxideAP Biology
  24. 24. I’m pretty super! Any questions?AP Biology

×