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Q.
Monds process is used for :
AFMCAFMC 2004
Solution:
Mond's process is used for the purification of nickel by converting it to volatile nickel carbonyl
$\underset{\text { Impure }}{ Ni }+4 CO \xrightarrow{80^{\circ} C } Ni ( CO )_{4} $
$ \xrightarrow{180^{\circ} C }\underset{\text { Impure }}{ Ni }+4 CO$
Aluminium is concentrated by Baeyer's process (chemical method) and reduced by electrolytic reduction (Hall's process) in which pure $Al$ is obtained at cathode.
$Fe$ is concentrated by hydraulic washing followed by calcination to remove moisture. It is then reduced by $CO$ (smelting) in a blast furnace.
$Fe _{2} O _{3}+2 CO \longrightarrow FeO + CO _{2}$
$FeO + CO \longrightarrow Fe + CO _{2}$
$Cu$ is obtained by oxidation of sulphide ore followed by self reduction.
$ Cu _{2} S +2 O _{2} \longrightarrow 2 CuO + SO _{2}$
$Cu _{2} S +2 Cu _{2} O \longrightarrow 6 Cu + SO _{2} \uparrow$
$Cu$ is further purified by electrolysis of $CuSO _{4}$ solution with impure $Cu$ as anode.