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Define thermite reaction? How it is used to join the crack railway track and machine parts |
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Answer» The reduction of a metal oxide to form metal by using aluminium powder as a reducing agent is called a thermite reaction. It is an exothermic reaction in which a large amount of heat is evolved. This reduction property of aluminium is used in thermite welding for joining the broken pieces of heavy iron objects like girders, railway tracks or cracked machine parts.Example: A mixture of iron (III) oxide and aluminium powder is ignited with a burning magnesium ribbon. Aluminium reduces iron oxide to produce molten iron metal with the evolution of heat.Fe2O3(s) + 2Al(s) → 2Fe(l) + Al2O3(s) + HeatThe molten iron produced is then poured between the broken iron pieces to weld them. Thermit is the reaction in which The amount of heat evolved is so large that the metals are produced in the molten state.The reaction of iron Oxide( Fe2O3)with aluminium is used to join railway track this can be shown as, :Fe2O3+ Al----Al2O3+ heat |
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