General Principles of Intellectual Property: Concepts of Intellectual Proper...
Unique properties of water
1.
2. Water
•Water is the most important
inorganic molecule
•All living organisms need water to
survive
•65% of human body weight is
water
3. Water and it’s importance
• Most important compound in living
organisms.
• Life processes rely on free movement of
molecules and ions.
– This occurs when substances are dissolved in
water.
• Water has unique properties that make it
vital to life.
– Many of water’s biological functions stem from
it’s chemical structure!
4.
5. Polarity of Water
• Atoms of water molecules are bonded together by
covalent bonds.
• Sharing of electrons in the covalent bonds is not
equal
– oxygen attracts electrons more strongly than hydrogen
• This gives water an assymetrical distribution of
charge.
– assymetrical = uneven
– Uneven opposite ends or poles are created
– POLAR covalent bonds exist within water molecules
8. Hydrogen bonds form
between water molecules
Oxygen is slightly
negative
(more electronegative)
Hydrogen is slightly positive
(less electronegative)
Neighboring
molecules held by
a hydrogen bonds
H-bonds are not true
bonds, but an
attractive force.
9.
10. Water is a versatile solvent
• When water and another solution are mixed,
you have an aqueous solution.
• Solute = what is being dissolved
• Solvent = what is doing the dissolving
• Polarity of water allows a variety of substances
to dissolve easily
– ionic compounds
– polar molecules
– Molecules with charged parts attract to water.
• Substances that repel water include non-polar
and non-ionic substances
• Salt dissolving
(animation)
11.
12.
13. Water as a solvent: Examples
• Polarity of water attracts other polar molecules
– ex: sugar
• These molecules are considered to be “hydrophilic”
or
– water loving
• Molecules that are non-polar are repelled
– Ex: oil
– Non-polar molecules are considered
“hydrophobic” or
– water fearing
• oil and water
animation
• More about dissolving
14. Importance to Living Things
• The chemistry of living things involves the
study of solutions ~~AQUEOUS solutions
• Water is vital to life because the chemical
reactions (metabolism) of living things must
take place in aqueous solutions.
• This occurs when substances are dissolved in
water.
• Life processes rely on free movement of
molecules and ions. (ex: electrical signals in
nervous systems)
15. Examples of aqueous solutions:
• Blood plasma
– Liquid portion only
– Ions, larger molecules, gases all dissolved in water
• Cytosol
– The gelatin-like aqueous solution inside cells.
• Interstitial fluid
– Intercellular fluid of multicellular organisms
~11 L in average adult human body
• Aquarium water….
16. Temperature Stabilizer
• Water can absorb great amount of heat before it’s
temperature changes considerably
– Due to hydrogen bonds
– Energy added to water disrupts hydrogen bonds
– Hydrogen bonds are constantly breaking and reforming
• Cells release heat as a result of metabolism
– Water helps to minimize temperature changes in cells
• This also allows large bodies of water and large organisms to
regulate temperature
– If bonds stay broken, water molecules at the surface escape into the
atmosphere
• Evaporation
• This takes away some energy and cools surface left behind
– This is why sweating cools you down!
17. High Specific Heat
Substance C (J/g o
C)
Air 1.01
Aluminum 0.902
Copper 0.385
Gold 0.129
Iron 0.450
Mercury 0.140
NaCl 0.864
Ice 2.03
Water 4.18
• Water (liquid) has a
high specific heat
compared to other
substances.
• It requires more heat
to increase it’s
temperature
• 0-100 degrees Celsius
range!
18.
19. Specific Heat Definiton:
• The quantity of heat required to raise the
temperature of a substance by one degree
Celsius is called the specific heat capacity
of the substance.
21. Freezing and Expansion
• Water expands below 4o
C.
• Molecules are spaced further apart
• It is less dense, therefore ice floats in
water.
• Ice at surface of lakes
and oceans provides a
thermal insulator for life
below the surface.
22.
23. Water is Cohesive
• Cohesion- ability of similar molecules to stick together
• Cohesion = stick TOGETHER
– Like molecules
– Like sticks to like
– WATER sticks to WATER
• Water attracts other water molecules
– Hydrogen bonds = attractions (water-water)
– Results in surface tension
24. Surface Tension
• Cohesion allows water to form an interface
with a surface.
• Surface tension is the measure of how
difficult it is to break this interface.
– Due to H-bonding between water molecules
• Ex: materials are able to rest on water (float),
as long as the surface tension is not broken.
25. Adhesion
• Sticking together of one substance to
another, different substance.
• Water is very adhesive; sticks to
OTHER substances like glue.
• Capillary action is adhesion and
cohesion in action.
– Capillary action is the process of pulling water
up against gravity in plant vessels
26.
27.
28. Imbibition
• Process of soaking into a hydrophilic
substance.
• Water soaking into seeds, paper towels,
or sponge.
• Important for plants (seed germination
usually requires imbibition)
29. pHpH
• pH refers to the dissociation of water
molecules.
• H2O H+
+ OH-
• In pure water, concentrations of H+ and OH-
are equal. (pH = neutral)
• Organisms are sensitive to changes in pH
30. AcidsAcids and BasesBases
• When acids dissolve in water they donate H+
to
the solution
• An acid is a substance that increases the H+
concentration
• A substance that reduces the H+
concentration
is a base
– By accepting H+
– Or by dissociating to form hydroxide ions that
combine with H+
to form water
31. pH
• In any solution, the product of H+
and OH-
concentrations is constant at 10 -14
[H+
][OH-
] = 10 -14
Neutral solution (pH 7) = [H+] = 10-7
[OH-] = 10-7
[10-7
] [10-7
] = 10-14
– If [H+] increased to 10-5
M, then [OH-] would be 10-9
M
[10-5
] [10-9
]= 10-14
32. PH Scale: pH scale is used to determine concentration
of these ions in a solution
Higher
concentration
of Hydrogen ions
H+
Higher
concentration of
Hydroxide ions OH-
33.
34. Each step
is ten fold
Ex: How many
more H+
at pH
of 1 than pH of
3?
10
x
10
= 100
35. pH Changes
• H+
and OH-
are very reactive
• pH changes greatly affect a cell’s proteins
and other molecules by altering their
structure (shape).
• If the structure of a molecule changes, the
result is a change in function.
In our pH lab, what changes were observed?
36. Buffers
• The control of pH is very important for
living systems
• Most chemicals of life can only operate
properly within a narrow pH range
• Buffers are substances that minimize
changes in pH
37. Buffers
• As shown on the pH scales above, the pH of
your internal body systems varies greatly.
– Stomach fluid = acidic
– Urine = acidic
– Intestinal fluid = alkaline
– Blood = alkaline
• Complex buffering systems maintain the
proper pH values of your body’s many fluids