The Element: ChlorineGeneral InformationWe researched the chemical element known as chlorine. Chlorine hasan atomic number of 17 and an atomic weight of 35. 453.
It has avalence number of 3. The element has 3 energy levels. Chlorine existsas a greenish-yellow gas at normal temperatures and pressures. Chlorineis second in reactivity only to fluorine among the halogen elements. Chlorine is a nonmetal.
It is estimated that 0. 045% of the earthscrust and 1. 9% of sea water are chlorine. Chlorine combines withmetals and nonmetals and organic materials to form hundreds ofchlorine compounds. Chlorine is about 2. 5 times as dense as air andmoderately soluble in water, forming a pale yellowish green solution.
Chlorine is so reactive that it never occurs free in nature. Chemical PropertiesChlorine is in the halogen family, and like all the otherhalogen elements chlorine has a strong tendency to gain one electronand become a chloride ion. Chlorine readily reacts with metals to formchlorides, most of which are soluble in water. Chlorine also reactsdirectly with many nonmetals such as sulfur, phosphorus, and otherhalogens.
Chlorine can support combustion; if a candle were to be throwninto a vessel of chlorine, it would continue to burn, releasing dense,black clouds of smoke, The chlorine combines with hydrogen of theparaffin, forming hydrogen chloride, and uncombined carbon is left inthe form of soot. Soot is black residue from fuel. Chlorine replacesiodine and bromine from their salts. Dry chlorine is somewhat inert ornot able to move, but moist chlorine unites directly with most of theelements. HistoryChlorine was discovered in 1774 by Karl Scheele.
Humphry Davyproved that chlorine was an element. Extensive production began 100years later. During the 20th Century. The amount of Chlorine used wasconsidered a measure of industrial growth. In, 1975 chlorineproductions ranked seventh on the list of largest-volume chemicalsproduced in the United States. The importance of chlorine has changedas new uses have been added.
In 1925 paper and pulp used over one-half . The chlorine made and chemical products only 10%. By the 1960spaper and pulp use accounted for only 15-17% and the chemical usesincreased to 75-80%. Peoples uses have contributed to the growth oflarge cities, and new textiles, plastics, paints, and miscellaneous useshave raised mans standard of living. Many large companies are basedprimarily on the manufacture of chlorine and its compounds. In 197817% of the United States production went into the production of vinylchloride monomer.
Other chlorinated organics consumed 48% of UnitedStates Production. Toxicity and PrecautionsChlorine was used in World War I as a poison gas. In factmost poisonous gases have chlorine in them. Chlorine is very corrosiveto moist tissue and has a very irritating effect on the lungs andmucous membranes of the nose and throat. Inhalation of chlorine gascan cause edema of the lungs and respiratory stoppage. When hydrogenand chlorine gases are mixed together, the mixture is stable if keptin a cool, dark place.
If heated or exposed to sunlight, the mixtureexplodes. Chlorine is easily liquefied and usually transported in itsliquid state in pressurized drums. Great care must be taken, however,to prevent the containers from bursting and liberating large amountsof the gas. In the United States most European countries, largequantities of chlorine may only be transported by train.
The presenttrend is to limit the transport of chlorine as much as possible byproducing and using the element in the same location. UsesChlorine has many great uses. Chlorine is an excellentoxidizing agent. At first.
The use of Chlorine was used as ableaching agent in the paper, pulp, and textile industries and as agermicide for drinking water preparation swimming pool purification, andhospital sanitation has made community living possible. Chlorine is used in bleaching as said before. The bleachingaction of chlorine in aqueous solution is due to the formation ofhypochlorous acid, a powerful oxidizing agent. If a colored, oxidizablematerial is present, hypochlorous acid releases its oxygen to oxidizethe material to a colorless compound. Liquid bleach is usually anaqueous solution of sodium hypochlorite, and dry powder bleachescontain 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 abilityof chloride of lime enables it to destroy bacteria; therefore largeamounts are used to treat municipal water systems. This chemical isalso used in swimming pools and for treating sewage. Chlorine is used as rock salt. Sodium chloride, NaCl, is useddirectly as mined (rock salt), or as found on the surface, or asbrine also known as salt water.
It can be dissolved, purified, andreprecipated or given in return for use in foods or when chemicalpurity is required. Its main uses are in the production of soda ashand chlorine products. The form uses it as refrigeration, dust, andice control, food processing, and food preservation. Calcium chloride,CaCl2, is usually obtained from salt water or as a by product ofchemical 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 chemistryand the chemical industry.
The chlorides of most metals are easilysoluble in water, which widens their applicability. Some otherimportant compounds are the chlorates, the perchlorates, and thehypochlorites. Hydrochloric acid is one of the most frequently usedacids. PreparationThe most important method for preparation of chlorine is theelectrolysis of a solution of common salt, sodium chloride. Thechlorine gas is liberated at the positive anode or positively chargedelectrode, which is made of graphite since a metal anode would reactwith chlorine. At the iron cathode or negatively charged electrode,sodium ions are reduced to sodium metal, which reacts immediately withwater to form sodium hydroxide.
Another method of preparing chlorine is by the electrolysis ofmolten salt. This process is used specifically to produce sodium, andthe chlorine is a commercial by product. When large quantities ofwaste hydrochloric and are available. Chlorine may be recovered byoxidation of the acid. This method has the advantage of convertinggreat quantities of waste acid to useful substances.
No matter what process is used to prepare chlorine, the gasmust be well dried. Dry chlorine is much less corrosive than moistchlorine gas. In the laboratory chlorine may be prepared by heatingmanganese oxide with hydrochloric acid. ConclusionIn conclusion chlorine is a very wonderful element. Chlorine hashundreds of compounds.
If we did not have these compounds we wouldnot have clean water, we would have an insect problem, we could notmake many important compounds that are used in medicine, and some ofthe battles in World War I might have been lost if it were not forchlorine. Our world would not be the same if not for chlorine.
