CHLORINE
Chlorine [Cl] 
CAS-ID: 7782-50-5 An:17 N: 18 Am: 35.453 g/mol Group No: 7 Group Name: Halogen Block: p-block Period: 3 State: gas at 298 K Colour: yellowish green Classification: Non-metallic Boiling Point 239.11K (-34.04°C) Melting Point: 171.6K (-101.5°C) Critical Temperature 417K (144°C) Density: 3.2g/l -Discovery Information -Who:Karl Wilhelm Scheele -When: 1774 -Where: Sweden -Name Origin Greek :khloros (green), "Chlorine" in different language -Sources Never found in free form in nature. Salt (sodium chloride, NaCl) is its most common compound. Chlorides make up much of the salt dissolved in the Earth's oceans - about 1.9% of the mass of seawater is chloride ions. -Abundance Universe: 1 ppm (by weight) Sun: 8 ppm (by weight) Carbonaceous meteorite: 380 ppm Earth's Crust: 130 ppm Seawater: 18000 ppm -Human: 1.2 x 106 ppb by weight 2.1 x 105 ppb by atoms -History Chlorine was discovered in 1774 by Swedish chemist Karl Wilhelm Scheele, who called it dephlogisticated muriatic acid and mistakenly thought it contained oxygen. Chlorine was given its current name in 1810 by Sir Humphry Davy, who insisted that it was in fact an element. Chlorine gas, also known as bertholite, was first used as a weapon in World War I by Germany on April 22, 1915 in the Second Battle of Ypres. As described by the soldiers it had a distinctive smell of a mixture between pepper and pineapple. It also tasted metallic and stung the back of the throat and chest. It was pioneered by a German scientist later to be a Nobel laureate, Fritz Haber. It is alleged that his role in the use of chlorine as a deadly weapon drove his wife to suicide. After its first use, it was utilized by both sides as a chemical weapon -Notes The pure chemical element has the physical form of a diatomic yellow-green gas, Cl2. Chlorine combines readily with nearly all other elements. Chlorine is about two and a half times as heavy as air. -Hazards Chlorine irritates respiratory systems especially in children and the elderly. In its gaseous state it irritates mucous membranes and in its liquid state it burns skin. As little as 3.5 ppm (parts per million) can be detected as an odour, and 1000 ppm is likely to be fatal after a few deep breaths. Toxic fumes may be produced when bleach is mixed with urine, ammonia (NH3), hydrochloric acid (HCl), or another cleaning product. These fumes consist of a mixture of chlorine gas, chloramine and nitrogen trichloride; therefore these combinations should be avoided. Over 2000 naturally-occurring organic chlorine compounds are known. Chlorine is very toxic to aquatic organisms. 
Chlorine Electrons per shell 2,8,7 Electron Configuration [Ne] 3s2 3p5 Ground state 2P°3/2 Atomic Volume 22.7 cm3 mol-1 Electronegativity 3.16 Magnetic ordering Non-magnetic Mas magnetic susceptibility -7.2 x 10-9 Molar magnetic susceptibility -2.55 x 10-10 Speed of Sound 206 m s-1
Flammability Non-flammable gas (strong oxidizer)
Vapour Pressure P (Pa) 1 10 100 1K 10K 100K T (K) 128 139 153 170 197 239 
Crystal Structure Structure Orthorhombic a = 622.35 pm b = 445.61 pm c = 817.85 pm α = 90° β = 90° γ = 90°
I/Physical properties
-Chlorine is a green-yellow, poisonous with choking smell gas
-Chlorine is not found on Earth as the free element.
-It occurs mainly as the compound rock salt,or sodium chloride
-Usually exist in gas state
-Mass of molecule is equal to 71
-Heavier than air (71>29)
-Soluble in water (the solution is called chlorine water)
II/Chemical properties
-Chlorine is acidic because chlorine reacts with wate to form two acids
Cl2 (g)+ H2O (aq) --> HCl (aq) + HOCl (aq)
-Chlorine water act as a bleach because the hypochlorous acid can lose its oxygen to other substances(it oxidises them.Many colored substances lose their colour when oxidised
2HOCl (aq) -> 2HCl (aq) + O2 (g)
Hydrogen burn in chlorine to form hydrogen chloride:
H2 (g) + Cl2 (g) --> 2HCl (g)
+Reaction with base:
+Reaction with acid:
+ Reaction with metal:
Chlorine combines with most metals ,forming metal chlorides.For emxample,it combines with burned iron to form iron (III) chloride
Apparatus:
-A ball of iron wool
-a flask containing chlorine gas
A ball of iron wool is heated and placed in a flask containing chlorine gas. The iron reacts vigorously with the chlorine to form a cloud of iron(III) chloride. After several minutes the iron(III) chloride formed by the reaction settles to the bottom of the flask. When the flask is rinsed with water the iron(III) chloride dissolves forming an orange solution.
Fe(s) + Cl2(g) à FeCl3 (s)
+Reaction with non-metal
Chlorine can reacts with another non-metal to form a compound which has covalent bond.
Apparatus:
-1 Beaker with chlorine inside
-1 capillary with hydrogen inside
-Aqueous of ammonia
Hydrogen gas flowing from a capillary is ignited. The watch glass covering a glass cylinder of chlorine is removed and the hydrogen flame lowered into the chlorine. The reaction between hydrogen and air is replaced by the reaction between hydrogen and chlorine, which produces hydrogen chloride. As the flame burns the level of chlorine gas in the container decreases. When a stopper from a bottle of aqueous ammonia is brought near the flame, white fumes of ammonium chloride are produced indicating the presence of hydrogen chloride.
H2 (g) + Cl2 (g) --> 2HCl (g)
+Reaction with another halogen
Chlorine can react with another halogen to form a compound which has covalent bonds.
Apparatus:
-1 test tube with iodine crystal inside
-1 capillary tube with chlorine inside.
Iodine crystals are placed at the bottom of a capillary tube. Chlorine gas is passed through the iodine crystals. The initial reaction between the chlorine and iodine forms iodine monochloride. The brown vapor of iodine monochloride can be seen flowing from the capillary. Dark brown iodine monochloride liquid is collected at the bottom of the test tube. As more chlorine is added, the brown iodine monochloride forms crystals of yellow iodine trichloride.
I2(s ) + Cl2(g ) --> 2 ICl(l )
2 ICl(l ) + 2 Cl2(g ) --> I2Cl6(s )
+Displacement reaction
Chlorine can react with a compound that has another halogen which is less reactive than chlorine to displace the halide and form a new compound.
Apparatus:
-An aqueous solution of chlorine
-An aqueous solution of idoide(I-)
-A test tube
-An aqueous solution of hexane
Iodide ion is added to chlorine water. By observing the color of the hexane layer, we see that the reaction has produced iodine.
(Note that the hexane layer is above the aqueous layer.)
2I-(aq ) + Cl2(aq ) --> 2Cl-(aq ) + I2(aq )
Chlorine and halogen are very reactive because their atoms are just one electron short of a full shell (in order to gain a stable form)-so they have a strong drive to gain an electron.However,chlorine is more reactive than iodine because its atom are smaller than iodine atoms-so the nucleus can attract an electron more strongly
III/How chlorine is made in industry
In nature, chlorine is found mainly as the chloride ion, a component of the salt that is deposited in the earth or dissolved in the oceans - about 1.9% of the mass of seawater is chloride ions. Even higher concentrations of chloride are found in the |
Industrially, elemental chlorine is usually produced by the electrolysis of sodium chloride dissolved in water. Along with chlorine, this chloralkali process yields hydrogen gas and sodium hydroxide, according to the chemical equation; |
2NaCl + 2H2O -->Cl2 + H2 + 2NaOH |
Chlorine can also be made by using brine,which is a concentrated solution of sodium chloride |
IV/USES
Used widely in paper product production, antiseptic, dyestuffs, food, insecticides, paints, petroleum products, plastics, medicines, textiles, solvents, and many other consumer products. Chlorine is an important chemical in some processes of water purification, disinfectants and in bleaches and chlorofluorocarbons (CFC).
To make plastic polyvinyl chloride (PVC)
To male hydrochloric acid
To make solvents such as tetrachloroethane (for dry cleaning)
In making medical drugs,bleaches,disinfectants,and insecticides.(Ex:C6H6Cl6)
To sterilize drinking water and water in swimming pools
To be used as a chemical weapon
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