Tag: production of metals

Questions Related to production of metals

Select the incorrect meaning of softening of lead.

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

  1. melting pure lead at high temperature

  2. removal of impurities, except silver, present in commerical lead

  3. formation of lead alloy

  4. formation of 100% pure lead

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Correct Option: A,C,D

Silver containing lead as an impurity is not purified by:

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

  1. Poling

  2. Cupellation

  3. Levigation

  4. Distillation

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Correct Option: A,C,D
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.

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

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

  1. (i) and (iv)

  2. (iii) and (iv)

  3. (i) and (iii)

  4. (i) and (ii)

Show answer
Correct Option: D
Explanation:

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

In the electrolytic refining of zinc,

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

  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

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Correct Option: D
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)

Aluminium is purified by :

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

  1. roasting

  2. sublimation

  3. electrolytic refining

  4. reduction with carbon

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Correct Option: C
Explanation:

Aluminium is purified by electrolytic reduction. Aluminium lies on the top of electrochemical series therefore it is purified by electrolytic refining.

Anode mud is obtained in which of the following processes?

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

  1. Roasting

  2. Zone refining

  3. Electrolytic refining

  4. Calcination

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Correct Option: C
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. 

Which of the following metal refined-electrolytically?

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

  1. $Al$

  2. $Na$

  3. $Cu$

  4. $Fe$

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Correct Option: A,C
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.

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

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

  1. $Na$

  2. $Au$

  3. $Cu$

  4. $Al$

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Correct Option: A
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.

The metal refined-electolytically is:

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

  1. $Al$

  2. $Na$

  3. $Cu$

  4. $Fe$

Show answer
Correct Option: C
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. 

Which of the following is purification method?

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

  1. Distillation

  2. Electrolytic process

  3. Filtration

  4. All of the above

Show answer
Correct Option: D
Explanation:
Purification is the physical separation of a chemical substance of interest from foreign or contaminating substances e.g. Filtration, centrifugation, evaporation, liquation, crystallization, adsorption, smelting, refining, distillation, fractionation, electrolysis, sublimation.