HOW TO OBTAIN HALOGENS

HOW TO OBTAIN HALOGENS

 Fluorine, chlorine and bromine  are in the nature as ions in salts, so we can oxide the ions to obtain the halogens.

2 X^1- -1e^-   ->   X₂.

Let us study one by one:

-Fluorine: It is the strongest element, so which element is going to oxide anion fluorine? There is not any element can do it, so we will use an electrolytic method using electricity. But what liquid will we use to dissolve the salt? If we use water, O^2- of the water will be oxide instead of F^1-.  We will have to dissolve the salt of fluorine in a solution formed by KF dissolved in HF.

 -Chlorine: We will use an electrolytic method using a concentrated solution of NaCl in water. The cathode is made of iron and the anode is made of graphite. Let us study the chemical reaction produced in both electrodes.

Cathode (oxidation, it is not a galvanic cell, it is an electrolytic cube):

2 Cl^1-  -  2 e^-  ->  Cl₂.

Anode:

Na¹⁺ + HO^1-  ->  NaOH

2 H¹⁺  + e^-  ->  H₂.

-Bromine: We will obtain bromine using bromides (salts) from the water in the sea. The oxidant agent will be chlorine molecule.

2 Br^1-  +  Cl₂  ->  Br₂  +  2 Cl^1-.

-Iodine: We will obtain iodine using “Chile Nitrate”, NaIO₃, using acids.

IO₃^1-  +  SO₂  ->  SO₄^2-  +  I^1-

IO₃^1-  +  I^1-  ->  I₂  +  H₂O

HALOGENS ARE USED FOR...

-Fluorine: to synthesize freons for freezers, Teflon, to rich uranium (UF₆), to make firebombs (IF₃), in water for drinking to avoid problems in teeth, caries problems (NaF).

-Chlorine: In water to avoid infections microorganisms (bacters). As bleach substances.

-Bromine: Bromide anions are used as sedative substances, it is also used to produce tears, and in photographs.

-Iodine: In ethanol, it is used to avoid infections in injuries.

It is also used to calculate the oxygen dissolved in water.

First of all we mix MnSO₄ and Mn(OH)₂

Later we add KI, and finally we empty some ml of concentrated H₂SO₄

Thanks to these reagents, ones we put H₂SO₄, each oxygen is inside water, one Iodide anion converts to iodine. So finally, we only have to know I₂ using Na₂S₂O₃ using starch to know the final point of the reaction.