Date post: | 24-Dec-2015 |
Category: |
Documents |
Upload: | emerald-madison-griffith |
View: | 215 times |
Download: | 0 times |
AP Biology 2007-2008
Water
The Molecule That Supports All Of Life
AP Biology
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
Noodle time!Do hydrogen bonds hold oxygenand hydrogen together IN water?
Pink – YesPurple – NoYellow – I’m not sure
AP Biology
Noodle time!What kind of bonds hold the hydrogen atoms to the oxygen atom in H2O?
Pink – Non-polar covalentPurple – HydrogenYellow – IonicGreen – Covalent
AP Biology
The Chemistry Of Water Molecules of water are held together by
Hydrogen bonds H+ of one water molecule attracted to O- of
another water molecule
AP Biology
The Properties Of Water (Super Powers)
1. Cohesion & Adhesion
2. Good Solvent
3. Low Density As A Solid
4. High Specific Heat
5. Heat Of Vaporization
6. Ionization of Water
I’m pretty super!
AP Biology
1.Cohesion
Try that with flour…or sugar…
Caused by the hydrogen bonds between H2O molecules
Makes water “sticky” Allows for this kid to drink out of his
straw And this guy to walk on water
AP Biology
1. Adhesion Caused by hydrogen bonding between
H20 and OTHER molecules Causes meniscus
AP Biology
Penny Challenge
AP Biology
TranspirationWater defies gravity and travels through plants from the roots up. Caused by COHESION & ADHESION!
AP Biology
2. Universal Solvent Solvents dissolve solutes creating solutions
The polarity of H2O makes it a good solvent
polar H2O molecules surround + & – ions pulling them apart
AP Biology
Noodle Time Is any kind of liquid a good solvent? Let’s try it! A
B
AP Biology
What do you notice?
AP Biology
Both A and B are POLAR.
Is C polar?
A
B
C
AP Biology
What do you notice? A = polar B = polar C = ?
AP Biology
What dissolves in water? Hydrophilic
substances have attraction to H2Opolar or non-polar?
AP Biology
What doesn’t dissolve in water? Hydrophobic
substances that don’t have an attraction to H2O
polar or non-polar?
fat (triglycerol)
AP Biology
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 hasmade all the difference!
AP Biology
Water vs Ice – Use the Water Kits
AP Biology
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 autumn
AP Biology
The Fireproof Balloon NOODLE TIME!
What will explode first?Pink - A balloon with H2OGreen - A balloon without H2O
Why did this happen?
AP Biology
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 Earth
AP Biology
5. Heat of vaporizationEvaporative cooling
Organisms rely on heat of vaporization to remove body heat
AP Biology
Alcohol vs. Water IN YO’ BODIES!
AP Biology
6. Ionization of water & pH Water ionizes
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 scalehow acidic or basic a solution is1 7 14
H2O H+ + OH–H2O H+ + OH–
AP Biology
pH Scale10–1
H+ IonConcentration
Examples of Solutions
Stomach acid, Lemon juice
1
pH100 Hydrochloric acid0
10–2 2
10–3 Vinegar, cola, beer3
10–4 Tomatoes4
10–5 Black coffee, Rainwater5
10–6 Urine, Saliva6
10–7 Pure water, Blood7
10–8 Seawater8
10–9 Baking soda9
10–10 Great Salt Lake10
10–11 Household ammonia11
10–12 Household bleach12
10–13 Oven cleaner13
10–14 Sodium hydroxide14
tenfold changein H+ ions
pH1 pH210-1 10-2
10 times less H+
pH8 pH710-8 10-7
10 times more H+
pH10 pH810-10 10-8
100 times more H+
AP Biology
I’m pretty super!
Any questions?