1. Leaching of gold is done using KCN , it is carried out in the presence of oxygen.
Au + H2O + O2 + KCN à K[Au(CN)2] + KOH
K[Au(CN)2] + Zn à K2[Zn(CN)4] + Au
2. Highly reactive metals like alkali metals Ca,Al etc are obtained using electrolytic refining method.
3. Zone Refining : It is a method of extraction of metals based on the principle that the metal crystallizes on being cooled but the impurities don't. Si,Ge are obtained using this method. We use a circular heater which when taken away from the impure metal takes away the impurities , and the pure metal is obtained in the crystalline form on the other end.
4. Van-Arkel Method of refining:
It is done to obtain ultra pure metals. Here the impure metal is treated with a suitable substance to convert it into a volatile compound which is decomposed to give pure metal. Eg Zr,Ti
Zr+I2àZrI4àZr+2I2
5. Electro refining : For highly reactive metals like alkali metals, here
anode:pure metal, cathode:impure metal, electrolyte : metal salt
6. Iron is the most abundant metal on earth due to it?s high binding energy. As the size of atom increases the binding energy becomes less and hence the metals become increasingly rare as we go along the periodic table.
7. Cu,Ag although less reactive can be found in combined state.
8. In froth floatation process : Mineral particles are wetted by pine oil, and the impurities by water.
Aniline and cresol are used as stabilizers.
NaCN is used as a depressant which stops the formation of certain substances in the froth formed. For eg it stops the formation of ZnS in presence of PbS.
9. Mond?s Process : purification of nickel.
Ni + COàNi(CO)4à(heat)?Ni(pure)
10. Important ores
Al : Bauxite (Al2O3.2H2O),
Ca:Limestone (CaCO3),
Na-Rock salt (NaCl),
Pb-Galena(PbS),
Tin-Casserite(SnO2),
Iron ? Haematite(Fe2O3)
11.Less reactive metals like Cu,Pb,Sn are reduced using CO
12. Moderately reactive metals like Fe,Cr,Mn are reduced using Al
13. CO is a better recing agent than C upto 1123K, above this temp C becomes a better reducing agent than CO
14. Amorphous silica can be prepared using reduction by magnesium :
SiO2+MgàMgO+Si
15. Non metals are generally oxidized before being extracted.
16. Extraction of reactive non metals like Cl and F is done electrolytically using NacL and KHF2 resp as electrolytes.
17. Bessemer?s converter is used for reducing Fe,Cu
18. Blast Furnace : Fe,Cu,Pb
19. Aluminothermic Reaction : Fe,Cr,Mn
20. Magnetic Separation : Fe,Cr,Mn
21. Roasting : Heating of ore in presence of air ZnS+O2àZnO+SO2
22. Calcination : CaCO3àheat?CaO+CO2
23. Smelting : Reduction of roasted of calcinated ores to give metal? Fe2O3+COàFe+CO2
24. Basic Flux : CaO, Acidic Flux:SiO3
25. Na has a yellow golden flame
26. Cu has a bluish green flame
27. Na is used in molten form in nuclear reactors as a collant, also used to prepare tetraethyl lead which is used for cracking of petrol
28. Mg is used for making an alloy named magnallin which is used in kitchen accessories, also used for cathodic protection of iron being more reactive than iron.
29. Mineral : Naturally occurring substances on the surface of the earth from which a metal may or maynot be extracted profitably. For eg Bauxite is a mineral from which aluminium can be extracted profitably but kolomite is a mineral from which it can?t be extracted profitably.
30. Poling : Impure metal is heated an stirred with greenwood. Greenwood contains hydrocarbons which reduce the metal and the impurities are separated out as gases.
31. Laughing gas : N2O
32. Dolomite : CaCO3 and MgCO3 mix
33. NaNO3 ? chile salt pepper
34. FeS2 ? Iron Pyrites
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