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