4.waters properties .ppt

1
Water Chemistry
All living organisms are dependent on water.
The structure of water is the basis for its
unique properties.
The most important property of water is the
ability to form hydrogen bonds

3
Water Chemistry
Within a water molecule, the bonds between
oxygen and hydrogen are highly polar.
Partial electrical charges develop:
- oxygen is partially negative

4
Water Chemistry
Hydrogen bonds are weak attractions
between the partially negative oxygen of
one water molecule and the partially
positive hydrogen of a different water
molecule.

7
Water Chemistry
The polarity of water causes it to be cohesive
and adhesive.
cohesion: water molecules stick to other water
molecules by hydrogen bonding
adhesion

10
Properties of Water
1. Water has a high specific heat.
- A large amount of energy is required to
change the temperature of water.
2. Water has a high heat of vaporization.

11
Properties of Water
3. Solid water is less dense than liquid water.
- Bodies of water freeze from the top down.
4. Water is a good solvent.

13
Properties of Water
5. Water organizes nonpolar molecules.
- hydrophilic: “water-loving”
-hydrophobic: “water-fearing”
- Water causes hydrophobic molecules to
aggregate or assume specific shapes.
6. Water can form ions.
H2O  OH-1 + H+1

15
Hydrogen bonding
(electric attraction)
Ice Liquid

16
“Dissociation” of water

17
pH
pH = – log [H+]
Log scale means 10X
change per unit!
[H+]= 10-1M
[H+]= 10-9 M

18
Buffers
Buffers resist changes to the pH of a
solution when H+ or OH- is added to the
solution.
Buffers accept hydrogen ions from the solution
when they are in excess and donate hydrogen ions
when they have been depleted. Physiologic buffers
include bicarbonate, orthophosphate and proteins.

19
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.

 Biological functions of Water
 Some biological functions of water are
listed below:
 Water is a vital body fluid that is essential
for regulating the processes like digestion,
transport of nutrients, and excretion.
20

 Water dissolves ionic and polar organic
compounds and allows the transportation
of the products of digestion to the place of
requirement in the body.
 Water regulates body temperature through
the process of sweating and evaporation.
21

 Water is the medium for all metabolic
reactions in the body as all metabolic
reactions in the body take place in the
solution phase.
 Water also provides habitat for various
animals in the form of ponds, rivers, seas,
etc.
22

 Water is essential for the germination of
seed and the process of photosynthesis by
which plants prepare their food.
 Water is the medium for the transport of
minerals from the soil to different parts of
plants.
23

 Water helps in the maintenance of the
plant structures by providing the
appropriate pressure to the plant tissues.
 Water also contributes to the formation of
various biological membranes by
interaction with various organic
compounds.
24

 Water also impacts the fundamental
components of all cells like DNA and
proteins where hydrogen bonding regulates
the folding of proteins and nucleic acids.
 The double helix structure of DNA is also
supported by water molecules that
surround the DNA in an ordered fashion.
25

4.waters properties .ppt

More Related Content

Similar to 4.waters properties .ppt (20)

More from mulenga22 (20)

Recently uploaded (20)

4.waters properties .ppt