ELECTROLYSIS Electrolysis is a method of using a direct electric current (DC) to drive an otherwise non-spontaneous chemical reaction.

Electrolysis is commercially highly important as a stage in the separation of elements from naturally occurring sources such as ores using an electrolytic cell

Applications of electrolysisLesson 9

Practical applications of electrolysisElectrolytic cells are used extensively in mining and other metallurgy-related industries.

– Electro-plating– Electro-refining– Electro-winning– Electrolytic production of Aluminum

Electro-winningIt’s a metallurgical term for the electrolytic recovery of a metal from a solution containing its ions.

The metal ions are reduced at the cathode where they deposit as metal.

Places where this is done are called “smelters”

In simple words ‘making metals’ !

Electroplating Purpose: to provide a surface property such as wear resistance, corrosion protection or lustre to a surface that lacks these properties.

It is basically coating a conductive material, such as a metal, with a thin layer of a different metal.

used in the manufacture of electronic and optic components and sensors, also in automobile parts, etc.

Zinc electroplating• cost-effective

• a protective coating to metallic substances such as nuts, bolts, fasteners, automotive parts, and many other hardware items.

• the use of zinc also improves the overall appearance of the metals, by giving them a variety of colors, a clean look, brightness, and a nice glowing shine.

Electro refining It is the electrolytic purification of a metal.

– The metal of an impure anode is oxidized and then the ions migrate to the pure cathode where they are reduced back to the metal.

– Impurities are left behind (anode mud or slime)

Aluminum production(Heroult-Hall Process)Aluminium is the most abundant metallic element, but it is rarely found in its elemental state. Its

primary commercial source is bauxite, a mixture of hydrated aluminium oxides and compounds of other elements such as iron.

Aluminium was made by heating ore along with elemental Na or K in a vacuum. The method was complicated and expensive

After initial purification, Al2O3.3H2O is left.

Water is driven off by heat.

Left with Al2O3 (Aluminum oxide, aka, alumina)

Al2O3 very impractical to electrolyze as its melting point is around 2050 C

.

These two chemists came to the rescue!

Aluminum production (Heroult-Hall Process)

Two 23-year-olds independently discovered that aluminum oxide dissolves in molten cryolite, Na3AlF6, adding this “flux” would lower the temperature to 1000 C

(A flux is a substance used to lower M.P of another substance)

Molten aluminum is then electrolyzed using carbon electrodes.

Aluminum is still very costly to produce as it consumes enormous electrical energy…

(Heroult-Hall Process)

Final notes• Re-read all those applications from your

textbook along with my notes for a full understanding.