How are non metals extracted explain with equations?
Metals can be categorized into three parts on the basis of their reactivity: most reactive, medium reactive and least reactive.
Extracting Metals in the Middle of the Activity Series
- The metals in the middle of the activity series (Zn, Fe, Pb, etc.) are moderately reactive.
- They are found in the earth’s crust mainly as oxides, sulphides or carbonates.
- It is easy to extract metal from their oxide, as compared to their sulphides and carbonates. Therefore before extracting metals form their respective ores, the metal sulphides and carbonates must be converted into metal oxides. For instance, sulphide and carbonate ores of zinc are heated to convert into their oxides.
- This conversion of sulphide ores into their oxides by heating strongly in the presence of excess air is known as roasting.
- This conversion of carbonate ores into their oxides by heating strongly in limited air in the presence of suitable reducing agents such as carbon is known as calcination.
- Sometimes displacement reaction is also used to derive the metal from their ores. Highly reactive metals displace the low reactive metals from their compounds. For instance, manganese dioxide is heated with aluminium powder.
The displacement reactions are highly exothermic and hence the metals are produced in the molten state. In fact, the reaction of iron (III) oxide (Fe2O3) with aluminium is used for joining railway tracks or cracked machinery parts. This reaction is known as the Thermit reaction.