The Exiting World Of Water Essay, Research Paper
Properties
Water(h 2 0)is a liquid at room temperature, is odorless,
tasteless, has a blush tint which may be detected; however, only in
layers of significant depth. The freezing point of water is 0
degrees Celsius(32 degrees Fahrenheit), and its boiling point is 100
degrees Celsius(212 degrees Fahrenheit). Water attains its maximum
density at a temperature of 4 degrees Celsius(39 degrees Fahrenheit)
and expands upon freezing.
Water is one of the best known ionizing agents. Because most
substances are somewhat soluble in water, it is frequently stated as
the universal solvent. Water combines with certain salts to form
hydrates. Water also reacts with metal oxides to form acids. It acts
as a catalyst in many important chemical reactions.
Occurrence
Water is the only substance now known to man, that can occur at
ordinary temperatures in all three states of matter, that is, as a
solid, a liquid, and as a gas.
As a solid, or ice, it is found as glaciers, and ice caps, on
water surfaces in winter, as snow, hail and frost, and as clouds
formed of ice crystals.
Water occurs in the liquid state as rain clouds formed of water
droplets, and on vegetation, or otherwise dew; in addition it covers
three covers of the surface of the earth in the form of swamps,
lakes, rivers, streams, ponds, oceans, etc.
As a gas, or in other words water vapor. It occurs as fog,
steam, and clouds. Atmospheric vapor is measured in terms of
relative humidity, which is the ratio of the quantity of vapor
actually present to the greatest amount possible at a given
temperature.
Life and Water
Water is a major constituent of living matter. From 50 to
90 percent of the weight of living organisms is water. Protoplasm,
the basis material of living cells, consists of a solution in water
of fats, carbohydrates, proteins, salts, and similar chemicals.
Water acts as a solvent, carrying, joining ,and chemically breaking
down these substances.
The Purification of Water
Hanging and dissolved impurities present in naturally occurring
water make it unsuitable for many purposes. Objectionable organic
and inorganic materials are removed by such methods as screening and
sedimentation to eliminate suspended materials; treatment with such
compounds as activated carbon to remove taste and odors; filtration;
and chlorination or irradiation to kill ineffective microorganisms.
In aeration, or the saturation of water with air in such a manner
as to produce greatest diffusion, usually by spraying water into the
air in fountains. Aeration removes odors and taste caused by
decomposing organic matter, and also industrial waste such as phenols
and volatile gases such as chlorine. It also converts dissolved iron
and manganese compounds into insoluble hydrated oxides of the metals
which may then be readily settled out.
Hardness of natural waters is caused largely by calcium and
magnesium salts and to a small extent by iron, aluminum, and other
metals. Hardness resulting from the bicarbonates and carbonates of
calcium and magnesium is called temporary hardness and can be removed
by boiling, which also sterilizes the water. The residual hardness
is known as noncarbonate, or permanent, hardness. The methods of
softening noncarbonate hardness include the addition of sodium
carbonate and lime and filtration through natural or artificial
zeolites which absorb the hardness-producing metallic ions and
release sodium ions to the water. Sequestering agents in detergents
serve to inactivate the substances that make water hard.
Iron, which causes a bad taste in drinking water, may be removed
by aeration and sedimentation or by passing the water through
iron-removing zeolite filters, or the iron may be stabilized by
addition of such salts as polyphosphates. For use in laboratory
applications, water is either distilled or demineralized by passing
it through ion-absorbing compounds.
THE EXITING WORLD
OF WATER