The Element Chlorine


The Element: Chlorine Essay, Research Paper

The Element: Chlorine

General Information

We researched the chemical element known as chlorine. Chlorine has

an atomic number of 17 and an atomic weight of 35.453. It has a

valence number of 3. The element has 3 energy levels. Chlorine exists

as a greenish-yellow gas at normal temperatures and pressures. Chlorine

is second in reactivity only to fluorine among the halogen elements.

Chlorine is a nonmetal. It is estimated that 0.045% of the earth?s

crust and 1.9% of sea water are chlorine. Chlorine combines with

metals and nonmetals and organic materials to form hundreds of

chlorine compounds. Chlorine is about 2.5 times as dense as air and

moderately soluble in water, forming a pale yellowish green solution.

Chlorine is so reactive that it never occurs free in nature.

Chemical Properties

Chlorine is in the halogen family, and like all the other

halogen elements chlorine has a strong tendency to gain one electron

and become a chloride ion. Chlorine readily reacts with metals to form

chlorides, most of which are soluble in water. Chlorine also reacts

directly with many nonmetals such as sulfur, phosphorus, and other

halogens. Chlorine can support combustion; if a candle were to be thrown

into a vessel of chlorine, it would continue to burn, releasing dense,

black clouds of smoke, The chlorine combines with hydrogen of the

paraffin, forming hydrogen chloride, and uncombined carbon is left in

the form of soot. Soot is black residue from fuel. Chlorine replaces

iodine and bromine from their salts. Dry chlorine is somewhat inert or

not able to move, but moist chlorine unites directly with most of the



Chlorine was discovered in 1774 by Karl Scheele. Humphry Davy

proved that chlorine was an element. Extensive production began 100

years later. During the 20th Century. The amount of Chlorine used was

considered a measure of industrial growth. In, 1975 chlorine

productions ranked seventh on the list of largest-volume chemicals

produced in the United States. The importance of chlorine has changed

as new uses have been added. In 1925 paper and pulp used over one-

half . The chlorine made and chemical products only 10%. By the 1960?s

paper and pulp use accounted for only 15-17% and the chemical uses

increased to 75-80%. Peoples uses have contributed to the growth of

large cities, and new textiles, plastics, paints, and miscellaneous uses

have raised man?s standard of living. Many large companies are based

primarily on the manufacture of chlorine and its compounds. In 1978

17% of the United States production went into the production of vinyl

chloride monomer. Other chlorinated organics consumed 48% of United

States Production.

Toxicity and Precautions

Chlorine was used in World War I as a poison gas. In fact

most poisonous gases have chlorine in them. Chlorine is very corrosive

to moist tissue and has a very irritating effect on the lungs and

mucous membranes of the nose and throat. Inhalation of chlorine gas

can cause edema of the lungs and respiratory stoppage. When hydrogen

and chlorine gases are mixed together, the mixture is stable if kept

in a cool, dark place. If heated or exposed to sunlight, the mixture

explodes. Chlorine is easily liquefied and usually transported in its

liquid state in pressurized drums. Great care must be taken, however,

to prevent the containers from bursting and liberating large amounts

of the gas. In the United States most European countries, large

quantities of chlorine may only be transported by train. The present

trend is to limit the transport of chlorine as much as possible by

producing and using the element in the same location.


Chlorine has many great uses. Chlorine is an excellent

oxidizing agent. At first. The use of Chlorine was used as a

bleaching agent in the paper, pulp, and textile industries and as a

germicide for drinking water preparation swimming pool purification, and

hospital sanitation has made community living possible.

Chlorine is used in bleaching as said before. The bleaching

action of chlorine in aqueous solution is due to the formation of

hypochlorous acid, a powerful oxidizing agent. If a colored, oxidizable

material is present, hypochlorous acid releases its oxygen to oxidize

the material to a colorless compound. Liquid bleach is usually an

aqueous solution of sodium hypochlorite, and dry powder bleaches

contain chloride of lime. Since chlorine destroys silk and wool,

commercial hypochlorite bleaches should never be used on these fibers.

Chlorine is also used as a disinfectant. The oxidizing ability

of chloride of lime enables it to destroy bacteria; therefore large

amounts are used to treat municipal water systems. This chemical is

also used in swimming pools and for treating sewage.

Chlorine is used as rock salt. Sodium chloride, NaCl, is used

directly as mined (rock salt), or as found on the surface, or as

brine also known as salt water. It can be dissolved, purified, and

reprecipated or given in return for use in foods or when chemical

purity is required. Its main uses are in the production of soda ash

and chlorine products. The form uses it as refrigeration, dust, and

ice control, food processing, and food preservation. Calcium chloride,

CaCl2, is usually obtained from salt water or as a by product of

chemical processing. Its main uses are road treatment, coal treatment,

and concrete conditioning.

In addition to these products, for which chlorine is needed,

various other chlorine compounds play an important part in chemistry

and the chemical industry. The chlorides of most metals are easily

soluble in water, which widens their applicability. Some other

important compounds are the chlorates, the perchlorates, and the

hypochlorites. Hydrochloric acid is one of the most frequently used



The most important method for preparation of chlorine is the

electrolysis of a solution of common salt, sodium chloride. The

chlorine gas is liberated at the positive anode or positively charged

electrode, which is made of graphite since a metal anode would react

with chlorine. At the iron cathode or negatively charged electrode,

sodium ions are reduced to sodium metal, which reacts immediately with

water to form sodium hydroxide.

Another method of preparing chlorine is by the electrolysis of

molten salt. This process is used specifically to produce sodium, and

the chlorine is a commercial by product. When large quantities of

waste hydrochloric and are available. Chlorine may be recovered by

oxidation of the acid. This method has the advantage of converting

great quantities of waste acid to useful substances.

No matter what process is used to prepare chlorine, the gas

must be well dried. Dry chlorine is much less corrosive than moist

chlorine gas. In the laboratory chlorine may be prepared by heating

manganese oxide with hydrochloric acid.


In conclusion chlorine is a very wonderful element. Chlorine has

hundreds of compounds. If we did not have these compounds we would

not have clean water, we would have an insect problem, we could not

make many important compounds that are used in medicine, and some of

the battles in World War I might have been lost if it were not for

chlorine. Our world would not be the same if not for chlorine.

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