Tag: basics of metallurgy

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Multiple choice chemistry production of metals refining of metals basics of metallurgy basic metallurgical processes

The method used in metallurgy to refine the impure metal is:

  1. Mond process

  2. Van Arkel process

  3. Liquation

  4. All of the above
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
$\text{Mond Method:}$ It is specially used for Ni. The vapour phase refining of Ni on heating in a stream of CO forms volatile $Ni(CO) _4$. These vapours when subjected to still higher temperature, decompose to give pure metal.

$\text{Liquation Method:}$ Pb, Sn, Bi, Zn etc are purified by this method. The metal has a low melting point and impurities have a high melting point. In an open hearth, the metal is heated to its melting point and metal melts down and impurities remain behind.

$\text{Van Arkel method}$: This method is used for ultrapure metals like Ti, Zr etc. The metal is converted into its volatile stable compound such as $TiI _4$, leaving behind impurities. The stable volatile compound thus formed is decomposed to get the pure metal.

Hence, option D is correct.
Multiple choice chemistry production of metals refining of metals basics of metallurgy basic metallurgical processes

Silver containing lead as an impurity is not purified by:

  1. Poling

  2. Cupellation

  3. Levigation

  4. Distillation
Reveal answer Fill a bubble to check yourself
A,C,D Correct answer
Explanation

Poling is a method employed in the purification of copper which contains cuprous oxide as an impurity. Silver containing lead as an impurity is not purified by polling.


Cupellation is a refining process in metallurgy, where ores or alloyed metals are treated under high temperatures and controlled operations to separate noble metals like gold and silver from base metals like lead, copper, zinc, arsenic or bismuth, present in the ore.

Levigation: The process of removal of heavy ore particles from lighter particles by washing with water. Silver containing lead as an impurity is not purified by levigation.in this process heavy ore particles are removed from a lighter particle. but not lighter particles from heavy particles.

Distillation is a process of separating the component substances from a liquid mixture by selective evaporation and condensation. Distillation may result in essentially complete separation (nearly pure components), or it may be a partial separation that increases the concentration of selected components of the mixture. Ex: zinc and mercury are distilled by a fractional distillation process.

So, silver-containing lead as an impurity is not purified by polling, levigation & distillation.

Hence options A, C, D are correct.

Multiple choice chemistry production of metals refining of metals basics of metallurgy basic metallurgical processes

Which of the following metals are obtained by electrolysis of their chlorides in molten state?
(i)   $Na$
(ii)  $Ca$
(iii) $Fe$
(iv) $Cu$

  1. (i) and (iv)

  2. (iii) and (iv)

  3. (i) and (iii)

  4. (i) and (ii)
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Sodium and calcium are the metals obtained by electrolysis of their chlorides in molten state. Both are reactive metals.

Multiple choice chemistry production of metals refining of metals basics of metallurgy basic metallurgical processes

In the electrolytic refining of zinc,

  1. graphite is at the anode

  2. the impure metal is at the cathode

  3. the metal ions gets reduces at the anode

  4. acidified zinc sulphate is the electrolyte
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

In the electrolytic refining of zinc

Anode → impure zinc

Cathode → strip of pure zinc

Electrolyte → acidified zinc sulphate solution

At anode → Oxidation of metal

                     (i.e., $Zn \longrightarrow Zn^{2+} + 2e^–$)

                            (impure)

At cathode → reduction of metal ions

                       (i.e., $Zn^{2+} + 2e^– \longrightarrow Zn$)

                          (Form solution)    (pure)

Multiple choice chemistry production of metals refining of metals basics of metallurgy basic metallurgical processes

Anode mud is obtained in which of the following processes?

  1. Roasting

  2. Zone refining

  3. Electrolytic refining

  4. Calcination
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Metals such as Cu, Ag, Zn, Sn, Pb, Al, Ni, Cr are refined by electrolytic refining method. The impure metal is made the anode of a electrolytic cell, while cathode is thin plate of pure metal. Electrolyte is the solution of a double salt of the metal. On passing the electric current pure metal from the anode dissolves and gets deposited at the cathode. The soluble impurities go into the solution while insoluble or less electropositive impurities settle down below the anode as anode mud or sludge. 

Multiple choice chemistry production of metals refining of metals basics of metallurgy basic metallurgical processes

Which of the following metal refined-electrolytically?

  1. $Al$
  2. $Na$
  3. $Cu$
  4. $Fe$
Reveal answer Fill a bubble to check yourself
A,C Correct answer
Explanation

The impure copper from a smelter is cast into a block to form the positive anode and the cathode is made up of purified copper. These are dipped into an electrolyte of copper sulphate solution. purification of aluminium can be carried out by the Hoopes process. This is an electrolytic process.

Multiple choice chemistry production of metals refining of metals basics of metallurgy basic metallurgical processes

Which of the following metals is not refined by electrolytic refining?

  1. $Na$
  2. $Au$
  3. $Cu$
  4. $Al$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The sodium and chloride produced in the electrolysis are kept from coming in contact with each other as the sodium is highly reactive and it must be prevented from coming in contact with oxygen as the metal quickly oxidizes under high temperature conditions.

Multiple choice chemistry production of metals refining of metals basics of metallurgy basic metallurgical processes

The metal refined-electolytically is:

  1. $Al$
  2. $Na$
  3. $Cu$
  4. $Fe$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Copper and zinc will be refined in electrolytic refining process for the following reasons.

$\rightarrow$ It meets the cost of refining 
$\rightarrow$ In more cases, electrolyte is selected which is the sulphate of the metal that is going to be refined.