Answers

2015-09-16T18:11:35+05:30
Thermit reactions :-
Sometimes reactive metals like Na, Ca, Al etc. are used as reducing agents to obtain metals from their oxides.   Eg :- 
3MnO
2  +  4Al ---------->   Mn  +  3Al2O3  +  Heat
  
The reaction between metal oxides and
aluminium is highly exothermic and the metals are obtained in molten state. Such reactions are called thermit reactions.
  The reaction between iron oxide and aluminium produces molten iron. This reaction is used to join rail tracks, broken machine parts etc.
Fe
2O3  +  2Al  ---------->     Al2O3  +  2Fe  +  Heat 
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