Water~

2. Human Life and Water
Is it possible to think of a human life without water ?
Many of you will say – No. Just not possible. While few
may say- Yes. But for a few hours. They are also right. So
it needs no further explanation that human being cannot
live for a pretty long time without water. He can live and
sustain life without food, but not without water.

3. Our body is nothing without water . Many of our
organs like human brain, lungs or blood constitute
more than 80% of water. We can realize the
importance of water only when we suffer from
dehydration. As long as our body is getting minimum
essential water supply it is functioning properly. All
the cells and organs in the body are dependant on
water for their effective functioning.

4. Water plays a great role in our body system. A look at
various functions can convince you of the same. Water
not only serves as a lubricant in our body system but also
helps to regulate the temperature of our body. It is the
most important element which plays a crucial role in
eliminating the waste from our body by detoxification.
Water also regulates the body mechanism .

5.  Water also has a role to play as disease preventive
tool. It is said that drinking 8-10 glasses of water each
day considerably reduces the risk of all sorts of cancers-
like colon cancer, breast cancer, bladder cancer etc.
 Water helps our body to absorb nutrients in the
intestines and it is the base material for saliva, which
plays important role in our digestive system. Water
carries oxygen and nutrients to all the body cells and
facilitates their effective functioning.
 Drinking water can reduce your hunger to certain
extent and help you to achieve the goal of weight loss. It
can stop you from overeating.

6.  Burning calories and fat
results in creation of toxins, and
water becomes essential to flush
them out of the body with the
help of kidneys.
 You need to pay attention
to your habit of drinking
water. It is better to start the day
with a glass full of water. It is
also advisable to drink some
water before exercise and even
during exercise if you feel tired
and fatigue. Always drink some
water after a gap of two-three
hours. It will help your body
system function efficiently.

7. Why Is Water the Universal Solvent?Water is called the universal solvent because more
substances dissolve in water than in any other chemical. This has
to do with the polarity of each water molecule. The hydrogen
side of each water (H2O) molecule carries a slight positive
electric charge, while the oxygen side carries a slight negative
electric charge. This helps water dissociate ionic compounds
into their positive and negative ions. The positive part of an
ionic compound is attracted to the oxygen side of water while
the negative portion of the compound is attracted to the
hydrogen side of water.Despite its name as the "universal
solvent" there are many compounds water won't dissolve or
won't dissolve well. If the attraction is high between the
opposite-charged ions in a compound, then the solubility will be
low. For example, most of the hydroxide exhibit low solubility in
water. Also, nonpolar molecules don't dissolve very well in water,
including many organic compounds, such as fats and waxes.

8.  Water pollution occurs mostly, when people overload
the water environment such as streams, lakes,
underground water, bays or seas with wastes or
substances harmful to living beings.
 Water is necessary for life. All organisms contain it,
some drink it and some live in it. Plants and animals
require water that is moderately pure, and they cannot
survive, if water contains toxic chemicals or harmful
microorganisms. Water pollution kills large quantity of
fish, birds, and other animals, in some cases killing
everything in an affected area.

9. Pollution makes streams, lakes, and coastal waters
unpleasant to swim in or to have a rest. Fish and shellfish
harvested from polluted waters may be unsafe to eat. People
who polluted water can become ill, if they drink polluted
water for a long time, it may develop cancer or hurt their
future children.
The major water pollutants are chemical, biological, and
physical materials that lessen the water quality. Pollutants
can be separated into several different classes:
The first class is petroleum products: oil, fuel, lubrication,
plastics. The petroleum products get into water by accidental
spills from ships, tanker trucks and when there are leaks from
underground storage tanks. Many petroleum products are
poisonous for animals. Spilled oil damages the feathers of
birds and the fur of animals, often it causes death.

10.  The third class are heavy metals, such as, mercury, selenium,
uranium, radium, cesium, etc. They get into the water from
industries, automobile exhausts, mines, and natural soil. Heavy
metals also become more harmful as they follow the food chain.
They accumulate in living being's cells and when they reach high
levels of concentration in the organism, they can be extremely
poisonous, or can result in long-term health problems. They can
s o m e t i m e s c a u s e l i v e r a n d k i d n e y d a m a g e .
 The fourth class is fertilizers and other nutrients used to promote
p l a n t g r o w t h o n f a r m s a n d i n g a r d e n s .
 The fifth class is infectious organisms and pathogens. They enter
water through sewage, storm drains, runoff from farms, etc.
 The last one is thermal pollution. Water is often taken from rivers,
lakes or seas to be used in factories and power plants. The water is
usually returned to the source warmer than when it was taken. Even
a small temperature change in a body of water can drive away the fish
and other species that were originally there, and attract other species
in place of them. It breaks a balance and can cause serious
c i r c u m s t a n c e s i n f u t u r e .

11.  The second class is pesticides and herbicides. There are
chemicals used to kill harmful animals and plants. If
they penetrate into streams, rivers, lakes, these chemicals
can be very dangerous. The chemicals can remain
dangerous for a long time. When an animal eats a plant
that's been treated with it, the poisons are absorbed into
t h e t i s s u e s a n d o r g a n s o f t h e a n i m a l s .
 When other animals feed on a contaminated animal,
the chemicals are passed up to them. As it goes up
through the food chain, the chemical becomes more
harmful, so animals at the top of the food chains may
suffer cancers, reproductive problems, and
death. Nitrates can cause a lethal form of anemia in
i n f a n t s .

12. Physical Properties of Water
We live on a planet that is dominated by water. More than
70% of the Earth's surface is covered with this simple
molecule. Scientists estimate that the hydrosphere contains
about 1.36 billion cubic kilometers of this substance mostly in
the form of a liquid (water) that occupies topographic
depressions on the Earth. The second most common form of
the water molecule on our planet isice. If all our planet's ice
melted, sea-level would rise by about 70 meters.
Water is also essential for life. Water is the major
constituent of almost all life forms. Most animals and plants
contain more than 60% water by volume. Without water life
would probably never have developed on our planet.

13. Water has a very simple atomic
structure. This structure consists
of two hydrogen atoms bonded
to one oxygen atom (Figure -1).
The nature of the atomic
structure of water causes its
molecules to have unique
electrochemical properties. The
hydrogen side of the water
molecule has a slight positive
charge (see Figure-1). On the
other side of the molecule a
negative charge exists. This
molecular polarity causes water
to be a powerful solvent and is
responsible for its strong surface
tension (for more information
on these two properties see the
discussion below).

14. Figure 1: The atomic structure of a water (or dihydrogen monoxide) molecule
consists of two hydrogen (H) atoms joined to one oxygen (O) atom. The unique way in
which the hydrogen atoms are attached to the oxygen atom causes one side of the
molecule to have a negative charge and the area in the opposite direction to have a
positive charge. The resulting polarity of charge causes molecules of water to be
a t t r a c t e d t o e a c h o t h e r f o r m i n g s t r o n g m o l e c u l a r b o n d s .
When the water molecule makes a physical phase change its molecules arrange
themselves in distinctly different patterns (Figure 8a-2). The molecular arrangement
taken by ice (the solid form of the water molecule) leads to an increase in volume and
a decrease in density. Expansion of the water molecule at freezing allows ice to float
o n t o p o f l i q u i d w a t e r .

16. Figure 2: The three diagrams above illustrate the distinct
arrangement patterns of water molecules as they change their
physical state from ice to water to gas. Frozen water
molecules arrange themselves in a particular highly
organized rigid geometric pattern that causes the mass of
water to expand and to decrease in density. The diagram
above shows a slice through a mass of ice that is one molecule
wide. In the liquid phase, water molecules arrange
themselves into small groups of joined particles. The fact that
these arrangements are small allows liquid water to move and
flow. Water molecules in the form of a gas are highly charged
with energy. This high energy state causes the molecules to
be always moving reducing the likelihood of bonds between
individual molecules from forming.

17. Water has several other unique physical
properties. These properties are:
Water has a high specific heat. Specific heat is the amount of
energy required to change the temperature of a substance.
Because water has a high specific heat, it can absorb large
amounts of heat energy before it begins to get hot. It also means
that water releases heat energy slowly when situations cause it to
cool. Water's high specific heat allows for the moderation of the
Earth's climate and helps organisms regulate their body
temperature more effectively.
Water in a pure state has a neutral pH. As a result, pure water is
neither acidic nor basic. Water changes its pH when substances
are dissolved in it. Rain has a naturally acidic pH of about 5.6
because it contains natural derived carbon dioxide and sulfur
dioxide.
Water conducts heat more easily than any liquid except
mercury. This fact causes large bodies of liquid water like lakes
and oceans to have essentially a uniform vertical temperature
profile.

18.  Water molecules exist in liquid form over an important
range of temperature from 0 - 100° Celsius. This range allows
water molecules to exist as a liquid in most places on our
planet.
 Water is a universal solvent. It is able to dissolve a large
number of different chemical compounds. This feature also
enables water to carry solvent nutrients
in runoff, infiltration, groundwater flow, and living
organisms.
 Water has a high surface tension (Figures 3 and 4). In
other words, water is adhesive and elastic, and tends to
aggregate in drops rather than spread out over a surface as a
thin film. This phenomenon also causes water to stick to the
sides of vertical structures despite gravity's downward pull.
Water's high surface tension allows for the formation of water
droplets and waves, allows plants to move water (and
dissolved nutrients) from their roots to their leaves, and the
movement of blood through tiny vessels in the bodies of some
animals.

19. Figure 3: The following illustration shows how water
molecules are attracted to each other to create high
surface tension. This property can cause water to exist as
an extensive thin film over solid surfaces. In the example
above, the film is two layers of water molecules thick.

20. Figure -4: The adhesive bonding property of water
molecules allows for the formation of water droplets

21.  Water molecules are the only substance on Earth that exist
in all three physical states of
matter: solid, liquid, and gas. Incorporated in the changes
of state are massive amounts of heat exchange. This feature
plays an important role in the redistribution of heat energy in
the Earth's atmosphere. In terms of heat being transferred
into the atmosphere, approximately 3/4's of this process is
accomplished by the evaporation and condensation of water.
 The freezing of water molecules causes their mass to
occupy a larger volume. When water freezes it expands
rapidly adding about 9% by volume. Fresh water has a
maximum density at around 4° Celsius (see Table-1). Water
is the only substance on this planet where the maximum
density of its mass does not occur when it becomes solidified.

22. Table -1: Density of water molecules at various
temperatures.
Temperature (degrees Celsius) Density (grams per cubic
centimeter)
0 (solid) 0.9150
0 (liquid) 0.9999
4 1.0000
20 0.9982
40 0.9922
60 0.9832
80 0.9718
100 (gas) 0.0006

23. What are the chemical properties of water?
What are the physical and chemical properties of
water that make it so unique and necessary for living
things? When you look at water, taste and smell it - well,
what could be more boring? Pure water is virtually
colorless and has no taste or smell. But the hidden
qualities of water make it a most interesting subject.

24. Water's Chemical Properties
You probably know water's chemical
description is H2O. As the diagram to the
left shows, that is one atom of oxygen
bound to two atoms of hydrogen. The
hydrogen atoms are 'attached' to one side
of the oxygen atom, resulting in a water
molecule having a positive charge on the
side where the hydrogen atoms are and a
negative charge on the other side, where
the oxygen atom is. Since opposite
electrical charges attract, water molecules
tend to attract each other, making water
kind of 'sticky.' As the right-side diagram
shows, the side with the hydrogen atoms
(positive charge) attracts the oxygen side
(negative charge) of a different water
molecule. (If the water molecule here looks
familiar, remember that everyone's favorite
mouse is mostly water, too).

25. All these water molecules attracting each other mean
they tend to clump together. This is why water drops are,
in fact, drops! If it wasn't for some of Earth's forces, such
as gravity, a drop of water would be ball shaped -- a
perfect sphere. Even if it doesn't form a perfect sphere on
Earth, we should be happy water is sticky.
Water is called the 'universal solvent' because it dissolves
more substances than any other liquid. This means that
wherever water goes, either through the ground or
through our bodies, it takes along valuable chemicals,
minerals, and nutrients.
Pure water has a neutral pH of 7, which is neither acidic
nor basic.