If all the rain drops were lemon drops and gum drops, oh what a rain that
would be
The Properties of Water
“the liquid of life”
You’re as
cold as ice
Raining on Sunday
Singing in
the rain
Rain drops on roses..whiskers on kittens
Let the rain fall
down and wake
my dreams
Its like rain on your
wedding day
When Chuck Norris goes swimming, he doesn’t get wet… the water gets Chuck
Property of Water
Cohesion
Adhesion
High Specific
Heat
Definition and Mechanics
Water molecules stick
together due to H bonds
Water molecules stick to
other polar molecules
due to H bonds
Water does not change temperature
quickly due to hydrogen bonds
preventing changes in molecular
movement
High Heat of
Vaporization
Water absorbs high quantity of heat
before it turns to a gas due to
hydrogen bonds
Less Density
as a Solid
Ice floats because the hydrogen
bonds maximize the distance
between molecules
High Surface
Tension
Hydrogen bonds keep water molecules
connected when exposed to air
The polar nature of water can dissolve any
polar molecule or isolate polar part on large
molecules
Solvent of Life
A) Hydrophilic : Water loving (polar)
B) Hydrophobic: Water hating (non-polar)
Biological Implications
Transpiration in plants
Transpiration in plants
Capillary movement
“cooler by the lake”
Blood used as heat transport
Evaporative cooling (Sweating)
Temperature stability in water
Keeps Aquatic organisms
alive during the winter
Insects walk on water
YouTube - Jesus lizard
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Water stays together as “drops”
Living things are 75% water.
Most biologically active
molecules are hydrophilic
Real or Fake?
Lack of injury to participants brought to you by Hydrogen Bonds
and the Emergent Properties of Water
Water and pH
1. What is pH?
The measurement of the Hydrogen (or hydronium)
ions found in a hydrophilic solution
2. Where do the H+ come from?
A small % of water molecules dissociate into
Hydronium (H3O+) and Hydroxide (OH-) ions
HOH
H+
+
OH-
3. How is pH measured?
pH = -log H+
Pure water H+
or
-7
-log of 1x10
= .0000001
= 1x10
-7
=7
Therefore: The pH of pure water is 7
The numbers on the pH scale
are in 10X increments
0 1
Increasing H+
Increasing OH-
(increasing Acid)
(increasing Basic)
2
3 4
5 6
7
8 9 10 11 12 13 14
4. What does pH have to do with Biology?
A) The pH of the environment can influence
biologically active molecules
1) influence chemical reactions
2) affect the interactions of hydrogen bonds
3) determine the structure of proteins
5. How do living organism control pH?
a) Living organism use “buffers” to regulate pH
b) Buffers work by donating or accepting H+
from the environment
H2CO3
Increasing OH-
HCO3 + H+
Increasing H+
Examples of buffers
1) organic “weak” acids
2) some proteins (albumin)
Slide 2
Ice
Water
Steam
Slide 2
Water Dissolving Ionic
Molecules
Water Dissolving Large
Molecules With Many
Polar Functional Groups
Slide 2