PowerPoint Presentation

							1
1+1 = 2

5+5=10

7+7=14



          2
    Discrepant Event Activity
D.E Inquiry-
 Problem: What would happen when
 you take equal amount of two liquids
 and add the two volumes together?

(Use D.E Activity Sheet to record
 responses).
                                        3
       Questions to Consider
1. Did the water or alcohol evaporate?
2. Was the water spilled when the test tube
   was inverted?
3. Did the liquids shrink or contract?




                                              4
          Theory behind DE
• Matter consists of molecules constantly in
  motion and there is a considerable space
  between these molecules. Overall, alcohol
  will dissolve into the water and slip right
  between water molecules = reduced
  volume.


                                                5
Atomic Structure/ Polarity




                             6
                 Cohesion

Water
molecules
stick to their
neighboring
water
molecules.
                            7
Another example of Cohesion: Dew
     drops on a spiders web.




                                   8
Adhesion
    • Water molecules stick
      to other molecules
    • Due to hydrogen
      bonding




                              9
Hydrogen bonding




                   10
Surface tension




                  11
Ice, water, vapor




                    12
     Hydrogen bonding
Ice
    (electric attraction)
                       Liquid




                                13
Universal solvent




                    14
  Universal Solvent:
“Dissociation” of water




                          15
Acids/ Bases                      [H+]= 10-1M
What is pH?
--potential for Hydrogen ions

--pH litmus paper only measures
liquid substances.




                                  [H+]= 10-9 M




                                            16
                            Overall lessons:
• Many properties of water are emergent properties due to hydrogen
  bonding.
• The cohesion of water molecules to each other is exploited by plants
  and animals.
• Water resists temperature changes by absorbing lots of heat.
• Lower density of ice causes it to float & insulate the water below.
• The polarity of water allows it to dissolve other polar molecules.
• Non-polar compounds are hydrophobic and not easily dissolved in
  water.
• A mole of a compound has a constant # of molecules.
• Adding or removing hydrogen ions changes the pH of a solution.
• Buffers resist pH changes by accepting or donating H ions when
  [H+] changes.

                                                                 17