Скачать или смотреть Chemistry Teacher | Isolation Of Fluorine : Dennis’ Method | Uses, Physical and Chemical Properties

Chemistry teacher explain the Isolation of Fluorine in easy and simple steps.
Symbol : F
Atomic number : 9
Period Number : 2
Valency : 1
Atomic mass : 19
Group Number : 17

Fluorine does not occur free in nature. It occurs in the combined form.

Dennis’ Method: This was devised by Dennis, Veeder and Rochow in 1931. In this fluorine is prepared by the electrolysis of fused sodium or potassium hydrogen fluoride (perfectly dry) Electrolysis is carried out between graphite electrodes in a V-shaped electrically heated copper tube. The ends of the tube are covered with copper caps into which the graphite electrodes are fixed with bakelite cement. The copper tube is thickly lagged to prevent the loss of heat.

Potassium Difluoride gives Potassium fluoride plus Hydrogen fluoride.

So Hydrogen is obtained at cathode and fluorine is obtained at anode.

So what is the outcome of the process.

Fluorine liberated at the anode is pass through the youtube containing sodium fluoride. This remove the hydrogen fluoride vapours coming with fluorine.

Sodium Fluoride plus Hydrogen Fluoride gives Sodium Hydrogen Fluoride.

Physical Properties
1. Fluorine is a gas and has pale greenish yellow colour.
2. It has extremely pungent and penetrating odour.
3. It is heavier than air.

Chemical Properties
Fluorine is the most active member of halogen family.

Action with Hydrogen: Hydrogen explodes violently in fluorine even in the dark.

Hydrogen plus Fluorine gives Hydrogen Fluoride.

Action with non-metals: Non-metals like carbon, silicon and phosphorus burn in fluorine forming fluorides.

Carbon plus Fluorine gives Tetra fluoromethane.

Silicon Plus Fluorine gives Silicon tetrafluoride.

Phosphorus plus Fluorine gives Phosphorus pentafluoride

Action with metals: It reacts with metals forming corresponding fluorides.

Silver plus Fluorine gives silver Fluoride
Aluminium plus Fluorine gives Aluminium Fluoride

Formation of Interhalogen compounds: It forms a variety of inter halogen compounds with other halogens.

Bromine plus Fluorine gives Bromine trifluoride
Iodine plus Fluorine gives Iodine Pentafluoride

Uses
1. Fluorine is used in the manufacture of a series of compounds known as freons. These non-toxic, non-combustible and volatile liquids are used as refrigerants in refrigerators, deep freezers and air conditioners. The most common, freon is known as dichlorodifluoro methane that is CF2 CL2.
2. CaF2 is used as flux in metallurgy.
3. NaF is used as a preservative to prevent fermentation and also for preventing dental cavities.
4. SF6 is used as an insulating material in high voltage equipment.
5. Teflon is used as container to store hydrofluoric acid.
6. UF6 is used in the separation of Uranium 235 from Uranium 238.