Mercury and Arsenic medals can be refined by
distillation while copper on iron can not be refined
by this method , give reason?
please help me it is very important
Answers
Answer:
OXIDATION REFINING - DEFINITION
On oxidation pure metal remains behind in molten form.Impurities is oxidized by air to their respective oxides.It is used for refining metals by oxidation of their impurities. e.g Iron.
LIQUATION REFINING - DEFINITION
On heating, pure metal liquefies and flows down the sloping furnace.Non-volatile impurities are infusible and remain behind.It is used for refining low melting point metals. e.g lead, tin.
METHODS OF REFINING OF COPPER - DEFINITION
Blister copper contains impurities of Ag and Au mainly.Impure copper is further refined electrolytically to obtain 99.95 to 99.97 % pure copper by using copper as anode, a rod of pure copper as cathode and acidified solution of CuSO4 as the electrolyte.
DISTILLATION REFINING - DEFINITION
On heating, pure metal vaporizes and is condensed and collected. Non volatile impurities remain behind.This method is used for refining volatile metals.e.g Mercury, Zinc.
EXPLAIN ELECTRO-REFINING OF COPPER - EXAMPLE
concept
In electrorefining of copper, impure copper is refined by electrolysis. In apparatus, aqueous copper sulphate solution is used as an electrolyte. Anode is made of impure copper and cathode is made of pure copper. At anode, copper is oxidized to copper ions. Copper ions in electrolyte migrate towards the cathode (pure copper) and get reduced. Thus, copper is deposited on the surface of a pure copper electrode.
ZONE REFINING - DEFINITION
A method of purifying a crystalline solid, typically a semiconductor or metal, by causing a narrow molten zone to travel slowly along an otherwise solid rod or bar to one end, at which impurities become concentrated.
VAPOUR-PHASE REFINING FOR NICKEL - DEFINITION
In this method to free a metal from impurities by first converting it into a suitable volatile compound, by heating it.
For heating two requirements are:
(i) the metal should form a volatile compound with a suitable reagent.
(ii) the volatile compound should be easily decomposable so that the recovery is easy.
Mond process is used for refining of nikel.
Ni+4CO
330−350K
Ni(CO)
4
→Ni+4CO
MOND PROCESS - DEFINITION
In this process nickel is heated in a stream of carbon monoxide to form nickel tetra carbonyl complex which is highly volatile. Then the complex is heated at high temperature to give pure metal.
Ni+4CO
330−350K
Ni(CO)
4
→Ni+4CO
VAN ARKEL FOR ZIRKONOIM - DEFINITION
This method is very useful for preparing pure metals by removing all the oxygen and nitrogen present in the form of impurity in certain metal like Zr and Ti which are used in space technology.
Reaction: Zr(s)+2I
2
(g)
870K
ZrI
4
(g)
Tungstanfilament
2075K
Zr(s)+2I
2
Same reaction pattern for Ti.
CHROMATOGRAPHY METHOD FOR REFINING - DEFINITION
This method is based on the principle of selective adsorption of the components of a mixture. It is the selective distribution of the components of a mixture between the two phases: moving phase and stationary phase. For refining nickel, column chromatography is used.
Explanation: