1. AGENDA 1. Bell Ringer 2. Go over Chemistry worksheet 3
AGENDA 1. Bell Ringer 2. Go over Chemistry worksheet 3. Notes over Water and pH 4.Water and pH worksheet
Objective:
I can identify the properties of water and understand what acids, bases, and buffers are in terms of Biology.

2. Chemistry of Life
Properties of Water

3. More about Water Why are we studying water? _______________________
inside & outside the cell

4. Chemistry of water H2O molecules form H-bonds with each other
____________________
creates a sticky molecule
APBio/TOPICS/Biochemistry/Movies AP/hydrogenbonds-Thinkwell.swf

5. Elixir of Life Special properties of water 1. cohesion & adhesion
surface tension, capillary action
2. _______________
many molecules dissolve in H2O
hydrophilic vs. hydrophobic
3. lower density as a solid
ice floats!
4. __________________
water stores heat
5. ___________________
heats & cools slowly
Ice! I could use more ice!

6. 1. Cohesion & Adhesion Cohesion _______________
H bonding between H2O molecules
water is “sticky”
______________
drinking straw
_______________
H bonding between H2O & other substances
capillary action
___________
water climbs up paper towel or cloth
Try that with flour… or sugar…

7. How does H2O get to top of trees?
Transpiration is built on cohesion & adhesion
APBio/TOPICS/04Biochemistry/MoviesAP/03_03WaterTransport_A.swf
Let’s go to the videotape!

8. 2. Water is the solvent of life
_________________________________
polar H2O molecules surround + & – ions
solvents dissolve solutes creating solutions
What dissolves in water easily?
polar or non-polar molecules?
How about Oxygen? Does that dissolve in H2O?

9. What dissolves in water?
______________________
substances have attraction to H2O
polar or non-polar?
What dissolves in water easily?
polar or non-polar molecules?
How about Oxygen? Does that dissolve in H2O?

10. What doesn’t dissolve in water?
_______________
substances that don’t have an attraction to H2O
polar or non-polar?
Oh, look hydrocarbons!
What dissolves in water easily?
polar or non-polar molecules?
How about Oxygen? Does that dissolve in H2O?
fat (triglycerol)

11. 3. The special case of ice
Most (all?) substances are more dense when they are solid, but
not water…
________________
_________________
And this has made all the difference!

12. Ice floats

13. Why is “ice floats” important?
Oceans & lakes don’t freeze solid
surface ice insulates water below
allowing life to survive the winter
_________________
ponds, lakes & even oceans would freeze solid
in summer, only upper few inches would thaw
________________________________
sinking cold H2O cycles nutrients in autumn

14. 4. Specific heat H2O resists changes in temperature
_________________
takes a lot to heat it up
___________________
H2O moderates temperatures on Earth

15. 5. ___________________ Evaporative cooling
Organisms rely on heat of vaporization to remove body heat

16. Ionization of water & pH
Water ionizes
H+ splits off from H2O, leaving OH–
if [H+] = [-OH], water is _______
if [H+] > [-OH], water is _______
if [H+] < [-OH], water is _______
pH scale
how acid or basic solution is
0  7  14
H2O  H+ + OH–

17. pH Scale H+ Ion Concentration Examples of Solutions pH
10–1
H+ Ion
Concentration
Examples of Solutions
Stomach acid, Lemon juice 1 pH
100
Hydrochloric acid
10–2 2
10–3
Vinegar, cola, beer 3
10–4
Tomatoes 4
10–5
Black coffee, Rainwater 5
10–6
Urine, Saliva 6
10–7
Pure water, Blood 7
10–8
Seawater 8
10–9
Baking soda 9
10–10
Great Salt Lake 10
10–11
Household ammonia 11
10–12
Household bleach 12
10–13
Oven cleaner 13
10–14
Sodium hydroxide 14
tenfold change in H+ ions
pH1  pH2
10-1  10-2
10 times less H+
pH8  pH7
10-8  10-7
10 times more H+
pH10  pH8
10-10  10-8
100 times more H+
In pure water only 1 water molecule in every 554 million is dissociated

18. Buffers & cellular regulation
pH of cells must be kept ~7
___________________________
shape of molecules affect function
________________________
Control pH by buffers
reservoir of H+
donate H+ when [H+] falls
absorb H+ when [H+] rises 1 2 3 4 5 6 7 8 9
Amount of base added
Buffering
range pH
Exercise = acidic in muscles
CO2 = carbonic acid
lactic acid
body uses buffers to counter act this

19. Any Questions? He’s gonna earn a Darwin Award!
Do one brave thing today…then run like hell!

20. Ice Fishing in Barrow, Alaska