Industrial Processes

Industrial Processes

Composition of air

Air is a mixture of gasses of different boiling points. This means that the gasses in air can be seperated if the air is liquified.

Composition of air
GasPercentage
Nitrogen78%
Oxygen21%
Carbon dioxide, water vapour, rare gases1%

Electrolysis

Electrolysis is the decomposition of an ionic compound using electricity. The compound being broken down is called the electrolyte. An electrolyte is a compound that conducts electricity either in solution or molten state. The conduction of the electricity is caused by the movement of ions. The electric current enters and leaves the electrolyte through electrodes, which are usually made of unreactive metals such as platinum or of the non-metal carbon (graphite).
These are said to be inert electrodes because they do not react with the products of electrolysis. Positively charged ions move away from the anode (the positive electrode) to the cathode (the negative electrode). Negatively charged ions move in the opposite direction.

Electrolysis of molten compounds containing two elements

Electrolysis of all molten ionic compounds of two elements follow the same general pattern:
The molten ionic compound is broken down to its elements, giving the metal at the cathode, and the non-metal at the anode.

Electrolysis of water

Pure water is a poor conductor of electricity. Ionic impurities in water increase its conductivity. Since water is a compound of hydrogen and oxygen only, electrolysis of water produces these two elements as expected.

Electrolysis

Electrolysis of water

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H2O

Overall equation of the electrolysis of water.

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Electroplating

Electroplating is the process of using electricity to coat one metal with another.

Electroplating

The metal to be plated is connected to the cathode in the electrolytic cell. The plating metal is made the anode, e.g. in copper plating copper is the anode. The atoms in the copper anode loses electrons an become copper ions Cu2+. The copper ions travel through the copper (ii) sulphate electrolyte to the cathode which is the object to be plated. At the cathode, the copper ions gain electrons and become copper atoms which the coat the cathode.

Common electroplating processes
SubstanceElectrolyteAnode reactionUse
CopperCopper (ii) sulphateCu → Cu2+ + 2eDecorative purposes and corrosion resistance
ChromiumChromic acidCr → Cr3+ + 3eDecorative purposes and corrosion resistance
NickelNickel (ii) sulphateNi → Ni2+ + 2eCorrosion resistance
TinTin (ii) sulphateSn → Sn2+ + 2eCorrosion resistance especially on food containers

Haber Process

Ammonia is manufactured from hydrogen and nitrogen by the haber proces.

Contact Process

Sulphuric acid is manufactured from sulphur dioxide by the contact process