Have you ever observed a pungent and irritating smell near a swimming pool or when a disinfectant is added to potable water? If yes, have you ever wondered what that smell is or what substance produces such a smell? In this article, we will study this substance – Chlorine.

Chlorine was discovered by Shale in 1774, when Shale is reacting with HCl and MnO, as a result of this reaction, he obtained chlorine, so it is said that chlorine was discovered by Shale. This reaction takes place as follows:

\(4\mathrm{HCL}+{\mathrm{MnO}}_2\rightarrow{\mathrm{Cl}}_2+{\mathrm{MnCl}}_2+2{\mathrm H}_2\mathrm O\)

After this, in 1810, a scientist named Davy studied the nature of chlorine in detail and named it chlorine due to the yellow colour of this element. It is a greenish-yellow gas with a pungent odour. Let’s study more about this gas in this article.

What is Chlorine Used For?

Chlorine is a chemical element with the symbol \({\rm{Cl}}\) and atomic number \(17.\) It has an average atomic mass of \(35.453\) amu and is the second most electronegative element after fluorine. In \(1774,\) the Swiss-German chemist Carl Wilhelm Scheele was the first to isolate this element by reacting hydrochloric acid with manganese (IV) oxide.

But it was Davy in \(1810\) who finally concluded that Scheele had made elemental Chlorine. The name Chlorine is derived from the Greek word “chloros”, which means “yellow-green.”

Chlorine is the second element of the halogen group of the periodic table that appears between fluorine and bromine, and therefore, its properties are mostly intermediate between them. It is a yellowish-green gas at room temperature and exists in nature as a diatomic molecule \({\rm{C}}{{\rm{l}}_{\rm{2}}}{\rm{.}}\) This arrangement allows two Chlorine atoms to share their outermost orbit electrons, making a covalent bond.

Position of Chlorine

Chlorine is placed as the \({\rm{1}}{{\rm{7}}^{{\rm{th}}}}\) element on the periodic table. It is located in period three and group \(17.\)

Occurrence of Chlorine

Chlorine is found in the Earth’s crust as well as in ocean water in abundance. In the ocean, Chlorine occurs as part of the compound sodium chloride \(\left( {{\rm{NaCl}}} \right){\rm{,}}\) also commonly known as table salt. In the Earth’s crust, it occurs as minerals in halite, carnallite and sylvite.

Study About Group 17 Elements

Atomic Structure of Chlorine

Chlorine has an atomic number \(17,\) which implies \(17\) electrons are revolving around the nucleus and \(17\) protons in the Chlorine atom. The electronic configuration according to electron distribution is \(2,8,7.\) It means that \(7\) electrons are in the outermost shell, that is M-shell. Thus, the Chlorine atom has \(7\) valence electrons, and it shows a valency of \(1.\) Also, it’s electronic distribution according to shell distribution is \({\rm{1}}{{\rm{s}}^{\rm{2}}}{\rm{2}}{{\rm{s}}^{\rm{2}}}{\rm{2}}{{\rm{p}}^{\rm{6}}}{\rm{3}}{{\rm{s}}^{\rm{2}}}{\rm{3}}{{\rm{p}}^{\rm{5}}}{\rm{.}}\)

Preparation of Chlorine

Chlorine can be produced on a large scale by several different methods. Some of the primary methods are:

1. By chlor-alkali process- It is an industrial process for the electrolysis solutions of sodium chloride in water. During this process, hydrogen is produced at the cathode and chlorine at the anode and at the same time, sodium hydroxide is produced in the electrolyte.

2. Deacon’s process is the oxidation of hydrogen chloride. Gaseous hydrogen chloride mixed with air or oxygen passes over pumice in contact with cupric chloride as a catalyst at a temperature of \({723\,\rm{K}}{\rm{.}}\)
\({\rm{4HCl + }}{{\rm{O}}_{\rm{2}}} \to {\rm{2C}}{{\rm{l}}_{\rm{2}}}{\rm{ + 2}}{{\rm{H}}_{\rm{2}}}{\rm{O}}\)

Properties of Chlorine

Physical Properties

1. It is a gas that appears greenish-yellow and has a pungent and irritating smell.
2. It is neither explosive nor flammable.
3. Under normal conditions, Chlorine is a gas that forms diatomic molecules.
4. It is \(2.5\) times heavier than air.
5. It is moderately soluble in water.
6. It has a boiling point of \({\rm{239}}{.11 \,\rm{K}}\) and a melting point of \({\rm{171}}{.6 \,\rm{K}}\) It is readily liquefied by cooling or by pressures of a few atmospheres at ordinary temperature.           
7. Chlorine displaces the heavier, less electronegative halogens, bromine and iodine, from compounds.

Chemical Properties

1. Reaction with water- Chlorine is slightly water-soluble and reacts with moisture to form hypochlorous acid \(\left( {{\rm{HClO}}} \right)\) and hydrochloric acid \(\left( {{\rm{HCl}}} \right){\rm{.}}\)
2. Reaction with Metals- Metals react with Chlorine to form ionic chlorides. For example- \({\rm{2Na + C}}{{\rm{l}}_{\rm{2}}} \to {\rm{2NaCl}}\)
3. Reaction with organic compounds- Chlorine reacts to form chlorinated derivatives with various organic compounds. Some of the reactions can be extremely violent, especially those with hydrocarbons, alcohols and ethers.

Isotopes of Chlorine

Isotopes are two or more types of atoms with the same atomic number and position in the periodic table but differ in mass numbers due to the different numbers of neutrons in their nuclei.
Chlorine has two stable isotopes, \( {}^ {35}_ {17} {\text{Cl}}\) \(\left( {{\rm{75}}{\rm{.77\% }}} \right)\) and \( {}^ {37}_ {17} {\text{Cl}}\) which gives Chlorine a standard atomic weight of \({\rm{35}}{.45\,\rm{amu}}{\rm{.}}\)

Uses of Chlorine

1. As a disinfectant: Chlorine-based disinfectants help keep water safe by destroying waterborne pathogens that can result in illnesses, such as diarrhoea, swimmer’s ear or skin rashes, including athlete’s foot.

2. As a bleaching agent: Chlorine is used to manufacture household Chlorine bleach, which whitens and disinfects clothes and disinfects kitchen and bathroom surfaces that are effective at killing germs that may be found on household surfaces that make people sick.

3. As a pesticide: It is used to prepare various pesticides that protect crops from being destroyed by insects.
Industries- It is used in the production of paper and paper products. It is used to manufacture plastics and dyes.

4. Medicines: It is used as an antiseptic as well as to produce drugs.

Some Interesting Facts

1. The Germans used Chlorine gas during World War I to poison the Allied soldiers.
2. Around \({\rm{1}}{\rm{.9\% }}\) of the ocean’s mass is composed of Chlorine atoms as saltwater.
3. The density of chlorine gas is \(2.5\) times greater than air.
4. Chlorine is used to make chlorofluorocarbons or CFCs which were once widely used in air conditioners and spray cans. However, since they contributed to destroying the ozone layer, their use has been mostly banned.
5. Most Chlorine gas for the industry is produced using electrolysis of water containing dissolved sodium chloride (salt water).

Learn About Aluminium Chloride Formula

What Does Chlorine Do to the Human Body?

Chlorine Poisoning: Chlorine is a chemical that prohibits bacterial growth in water. Chlorine poisoning can occur through touch, swallowing, or inhaling Chlorine. It reacts with water that can cause the formation of hydrochloric acid and hypochlorous acid outside of the body and on mucosal surfaces inside the body- including the water in our digestive tract. Both of these acids can be highly poisonous to humans.

1. Respiratory symptoms include coughing, difficult breathing, and fluid inside the lungs.
2. Digestive system symptoms include burning the mouth, throat pain, stomach pain, vomiting, blood in the stools.
3. Circulatory system symptoms include changes in the pH balance of the blood, severe injury to the eyes, skin damage- resulting from tissue injury with burns and irritation.

Summary

From this article, we learned that Chlorine exists mainly in salts and minerals and is the second most electronegative element. Therefore, it is advantageous and also one of the most harmful substances for the human body. If you have any questions about this article or, in general, about Chlorine, ping us through the comments section, and we will get back to you as soon as possible.

FAQs on Chlorine

Q.1. What does Chlorine do to the human body?
Ans: Chlorine is a chemical that inhibits bacterial growth in water. Chlorine poisoning can occur through touch, swallowing, or inhaling Chlorine. It reacts with water to form hydrochloric acid and hypochlorous acid outside of the body and mucosal surfaces inside the body- including the water in our digestive tract. Both of these acids can be highly poisonous to humans.
a. Respiratory symptoms include coughing, difficult breathing, and fluid inside the lungs.
b. Digestive system symptoms include burning in the mouth, throat pain, stomach pain, vomiting, blood in the stools.
c. Circulatory system symptoms include changes in the pH balance of the blood, severe injury to the eyes, skin damage- resulting from tissue injury with burns and irritation.

Q.2. What is Chlorine used for?
Ans: Some of the uses of Chlorine are as follows:
1. As a disinfectant.
2. It is used as a bleaching agent at homes and in various industries.
3. It is used in the manufacture of plastics and dyes.
4. It is used for the preparation of pesticides.
5. It is used in the preparation of various chemicals like hydrochloric acid.
6. It is used for the preparation of medicines.

Q.3. What is the Chlorine formula?
Ans: The chemical formula for Chlorine is \({\rm{C}}{{\rm{l}}_{\rm{2}}}{\rm{.}}\)

Q.4. Is Chlorine \({\rm{Cl}}\) or \({\rm{C}}{{\rm{l}}_{\rm{2}}}{\rm{?}}\)
Ans: Chlorine exists in nature as a diatomic molecule \({\rm{C}}{{\rm{l}}_{\rm{2}}}{\rm{.}}\) This arrangement allows two Chlorine atoms to share their outermost orbit electrons, making a covalent bond between them.

Q.5. Is Chlorine acidic or basic?
Ans: Chlorine gas is neither acidic nor basic. The aqueous solution of Chlorine is acidic because of the presence of hydronium ions in the solution. 

Q.6. What are three interesting facts about Chlorine?
Ans: The three interesting facts about Chlorine are as follows:
Chlorine is the third most abundant element in the Earth’s oceans. It is the ninth most abundant element in the human body. Most Chlorine gas for the industry is produced using electrolysis on water containing dissolved sodium chloride (salt water).

We hope this article on Chlorine helps you. If you face any issue regarding the same, do let us know about it in the comments section below and we will get back to you soon.