Which one of the following is most likely a mismatch?
(1) Zinc – Liquation           (2) Copper – Electrolysis          (3) Titanium – van Arkel Method           (4) Nickel – Mond process


Answer: Option 1
Solution:

(1) Liquation: This method, is employed to remove the impurities with high melting points from metals  having relatively low melting points such as tin (Sn; mp= 904 K), lead (Pb; mp=600 K), mercury (Hg; mp=234 K), and bismuth (Bi; mp=545 K). In this process, the crude metal is heated to form fusible liquid and allowed to flow on a sloping surface. The impure metal is placed on sloping hearth of a reverberatory furnace and it is heated just above the melting point of the metal in the absence of air, the molten pure metal flows down and the impurities are left behind. The molten metal is collected and solidified.

Which one of the following is most likely a mismatch


(2) Electrolysis: The crude metal is refined by electrolysis. It is carried out in an electrolytic cell containing aqueous solution of the salts of the metal of interest. The rods of impure metal are used as anode and thin strips of pure metal are used as cathode. The metal of interest dissolves from the anode, pass into the solution while the same amount of metal ions from the solution will be deposited at the cathode. During electrolysis, the less electropositive impurities in the anode, settle down at the bottom and are removed as anode mud.  Metals such as Silver, copper, zinc etc.,can also be refined by this process

Which one of the following is most likely a mismatch


(3) Van-Arkel Method: This method is very useful for removing all the oxygen and nitrogen present in the form of impurity in certain metals like Zr and Ti. The crude metal is heated in an evacuated vessel with iodine. The metal iodide being more covalent, volatilizes. The metal iodide is decomposed on a tungsten filament, electrically heated to about 1800K. The pure metal is thus deposited on the filament.

Which one of the following is most likely a mismatch

(4) Mond Process: The impure nickel is heated in a stream of carbon monoxide at around 350 K. The nickel reacts with the CO to form a highly volatile nickel tetracarbonyl. The solid impurities are left behind.

Which one of the following is most likely a mismatch

On heating the nickel tetracarbonyl around 460 K, the complex decomposes to give pure metal.

Which one of the following is most likely a mismatch



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