All About Chlorine
The element of chlorine was first discovered by Swedish chemist Carl Wilhelm Scheel. But at that time, people thought that this gas is a compound containing oxygen element. Thanks to research conducted by Sir Humphry Davy, it is evident that the gas found by Scheel contains no oxygen, but contains a new element called chlorine.
Chlorine is a member of the halogen group. In nature, chlorine is a diatomic molecule in the form of gas. The name of chlorine comes from the Greek word "chloros" which means green. The name is adapted to the color of chlorine gas that is pale green.
As one element of halogen, chlorine is also highly reactive. But the reactivity is lower than fluorine. Chlorine can react with many elements in the periodic table. Usually, the product of the reaction contains the element with the highest oxidation number.
As an example :
Burning iron in chlorine gas produces iron (III) chloride, not iron (II) chloride.
2 Fe (s) + 3Cl2 (g) ==> 2 FeCl3 (s)
Phosphorus burning in chlorine gas produces phosphorus pentachloride compounds.
2 P (s) + 5 Cl2 (g) ==> 2 PCl5 (s)
Chlorine gas is very easy to make in the laboratory. We can react concentrated hydrochloric acid with potassium permanganate solids to produce chlorine gas. Potassium permanganate is an oxidizing agent. The chloride ion will oxidize to form chlorine gas (Cl2) while the permanganate ion will be reduced to produce manganese (II) ions.
Oxidation reaction: 2 HCl (aq) ==> 2H + (aq) + Cl2 (g) + 2e
Reduction reaction: MnO4- (aq) + 8H + + 5e ==> Mn2 + (aq) + 4H2O (l)
One of the uses of chlorine gas is as a chlorinating agent. Reacting an organic compound with chlorine gas will produce an organic compound that binds some chlorine atoms.
Example:
The reaction between ethene and chlorine gas will produce 1,2-dichloroethane compounds.
CH2 = CH2 (g) + Cl2 (g) ==> CH2Cl - CH2Cl (g)
Chlorine has a positive standard reduction potential. This makes chlorine gas one of the strongest oxidizing agents.
Chlorine gas is highly toxic. With a concentration of about 30 ppm only, if we are exposed to this gas within half an hour, then the consequences can be fatal. Death can occur due to chlorine gas poisoning. In the world war, Germany used chlorine gas as a mass killer. In 1915, an estimated 5,000 allied soldiers were killed by chlorine gas poisoning.
Industrially, chlorine gas is prepared using electrolysis method of salt or sodium chloride solution. The cheapest source of sodium chloride solution is from seawater.
In the process, the chloride ions from NaCl will oxidize to chlorine gas, while the sodium ions will be reduced. The by-product of chlorine gas preparation is sodium hydroxide (NaOH).
Most chlorine gas production is used to make organochlorine compounds. In addition, chlorine gas is also used in the pulp and paper industry. The use of chlorine gas in the paper industry is as bleach.
Chlorine is also used in water treatment processes. Chlorine can kill germs and bacteria contained in water. But according to research, the use of chlorine in the water treatment process has a negative impact. Chlorine can actually react with organic molecules contained in water. These organic molecules are toxic and harmful to humans.
Based on these studies, the use of chlorine in the process of water treatment and papermaking is no longer allowed.
Chlorine is a member of the halogen group. In nature, chlorine is a diatomic molecule in the form of gas. The name of chlorine comes from the Greek word "chloros" which means green. The name is adapted to the color of chlorine gas that is pale green.
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| Wikimediacommons.org |
As an example :
Burning iron in chlorine gas produces iron (III) chloride, not iron (II) chloride.
2 Fe (s) + 3Cl2 (g) ==> 2 FeCl3 (s)
Phosphorus burning in chlorine gas produces phosphorus pentachloride compounds.
2 P (s) + 5 Cl2 (g) ==> 2 PCl5 (s)
Chlorine gas is very easy to make in the laboratory. We can react concentrated hydrochloric acid with potassium permanganate solids to produce chlorine gas. Potassium permanganate is an oxidizing agent. The chloride ion will oxidize to form chlorine gas (Cl2) while the permanganate ion will be reduced to produce manganese (II) ions.
Oxidation reaction: 2 HCl (aq) ==> 2H + (aq) + Cl2 (g) + 2e
Reduction reaction: MnO4- (aq) + 8H + + 5e ==> Mn2 + (aq) + 4H2O (l)
One of the uses of chlorine gas is as a chlorinating agent. Reacting an organic compound with chlorine gas will produce an organic compound that binds some chlorine atoms.
Example:
The reaction between ethene and chlorine gas will produce 1,2-dichloroethane compounds.
CH2 = CH2 (g) + Cl2 (g) ==> CH2Cl - CH2Cl (g)
Chlorine has a positive standard reduction potential. This makes chlorine gas one of the strongest oxidizing agents.
Chlorine gas is highly toxic. With a concentration of about 30 ppm only, if we are exposed to this gas within half an hour, then the consequences can be fatal. Death can occur due to chlorine gas poisoning. In the world war, Germany used chlorine gas as a mass killer. In 1915, an estimated 5,000 allied soldiers were killed by chlorine gas poisoning.
Industrially, chlorine gas is prepared using electrolysis method of salt or sodium chloride solution. The cheapest source of sodium chloride solution is from seawater.
 |
| Wikimediacommons.org |
In the process, the chloride ions from NaCl will oxidize to chlorine gas, while the sodium ions will be reduced. The by-product of chlorine gas preparation is sodium hydroxide (NaOH).
Most chlorine gas production is used to make organochlorine compounds. In addition, chlorine gas is also used in the pulp and paper industry. The use of chlorine gas in the paper industry is as bleach.
Chlorine is also used in water treatment processes. Chlorine can kill germs and bacteria contained in water. But according to research, the use of chlorine in the water treatment process has a negative impact. Chlorine can actually react with organic molecules contained in water. These organic molecules are toxic and harmful to humans.
Based on these studies, the use of chlorine in the process of water treatment and papermaking is no longer allowed.
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