Tag: refining of metals

Questions Related to refining of metals

Which of the following is not a method of refining of metals?

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

  1. Electrolysis

  2. Smelting

  3. Poling

  4. Liquation

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Correct Option: B
Explanation:

Smelting is process in which metal is extracted from its ore by heating and melting. It is not a method of refining metal. Methods of refining metals are electrolysis poling, liquation, zone refining, vapour phase refining, distillation.

Which one of the following is the true in electrolytic refining?

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

  1. Impure metal is made cathode.

  2. Impure metals is made anode.

  3. Impure metals is made cathode and pure metal as anode.

  4. Both electrodes must be of pure metal.

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Correct Option: B
Explanation:
  • In Electrolytic refining, the impure metal is made to act as an anode. A strip of the same metal in pure form is used as a cathode. 
  • They are put in a suitable electrolytic bath containing a soluble salt of the same metal. 
  • The more basic metal remains in the solution and the less basic ones go to the anode mud.
  • Zinc, copper is refined by this method.

Four metals and their methods of refinement are given
(i) $Ni,\ Cu,\ Zr,\  Ga$
(ii) Electrolysis, van Arkel process, zone refining, Mond's process
Choose the right method for each:

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

  1. $Ni:$ Electrolysis, $Cu:$ van Arkel process, $Zr:$ Zone refining, $Ga:$ Mond's process

  2. $Ni:$ Mond's process, $Cu:$ Electrolysis, $Zn:$ van Arkel process, $Ga:$ Zone refining

  3. $Ni:$ Mond's process, $Cu:$ van Arkel process, $Zr:$ Zone refining, $Ga:$ Electrolysis

  4. $Ni:$ Electrolysis, $Cu:$ Zone refining, $Zr:$ van Arkel process, $Ga:$ Mond's process

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Correct Option: B
Explanation:

$Ni$ is refined by Mond's process.

$Cu$ is refined by Electrolysis.
$Zn$ is refined by Van Arkel process.
$Ga$ is refined by Zone refining.

Mark the correct statements:

(i) mercury can be refined by the process of distillation.

(ii) In poling, the molten impure metal is stirred with green poles of wood.

(iii) In electrolyte refining of metals, impure metal is made as cathode and a thin strip of pure metal is made as anode.

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

  1. (i) and (ii)

  2. (i) and (iii)

  3. (ii) and (iii)

  4. (i), (ii) and (iii)

Show answer
Correct Option: A
Explanation:

Low boiling point metals like Mercury are purified with distillation.

Hence,  statement (i) is correct.
 
The heat of  copper makes the pole emit wood gas that reduces the cuprous oxide to copper.
In poling, the molten impure metal is stirred with green poles of wood.
Hence,option (ii) is correct.

In electrolyte refining of metals, impure metal is made as Anode  and a thin strip of pure metal is made as cathode.
Hence, option (iii) is incorrect.

Electrolysis is used for refining certain metals such as copper and zinc.

chemistry metals and non metals refining of metals basics of metallurgy basic metallurgical processes

  1. True

  2. False

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Correct Option: A
Explanation:

Electrolysis, process by which electric current is passed through a substance to effect a chemical change. The chemical change is one in which the substance loses or gains an electron (oxidation or reduction).

It is extensively used in metallurgical processes, such as in extraction (electrowinning) or purification (electrorefining) of metals from ores or compounds and in deposition of metals from solution (electroplating). Electrolysis of salt of copper and zinc results in the deposition of pure copper and zinc on cathode of the electrolytic cell.
option A is correct

'Softening of lead' means ___________.

chemistry metals and non metals refining of metals basics of metallurgy basic metallurgical processes

  1. conversion of lead to $PbO$

  2. conversion of lead to $Pb _{3}O _{4}$

  3. removal of impurities(metallic) from lead

  4. washing lead with $HNO _{3}$ followed by alkali solution

Show answer
Correct Option: C
Explanation:

The removal of  metallic impurities from lead is known as 'Softening of lead'.

In the electrolytic refining of a metal M, what would you take as the anode is : 

chemistry metals and non metals refining of metals basics of metallurgy basic metallurgical processes

  1. impure metal M

  2. thin strip of pure metal M

  3. solution of salt of the metal M

  4. none of these

Show answer
Correct Option: A
Explanation:

The purest copper is obtained by an electrolytic process using impure copper as the anode and a thin sheet of pure copper as cathode. The electrolyte is an acidic solution of copper sulphate. By passing electricity copper is dissolved from anode and deposits at cathode.

On the basis of following features identify the correct option:
I. This metal is not obtained in free state.
II. This metal is obtained by electrolysis of their chlorides in molten state.

chemistry metals and non metals refining of metals basics of metallurgy basic metallurgical processes

  1. $Na$

  2. $Ca$

  3. both (1) and (2)

  4. neither (1) nor (2)

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Correct Option: C
Explanation:

Both Sodium and calcium are highly reactive metal oxides are not reduced by carbon and these metals are obtained in free state by electrolytic reduction of their molten chloride salts.

In electrolytic refining, which one is the anode and which is cathode?

chemistry metals and non metals refining of metals basics of metallurgy basic metallurgical processes

  1. Pure metal is the anode and impure metal is cathode

  2. Impure metal is made anode and pure metal cathode

  3. Both can be done interchangeably

  4. None of the above

Show answer
Correct Option: B
Explanation:

In electrolytic refining, impure metal is made the anode and a thin strip of pure metal is made the cathode.

Why refining of metals is required?

chemistry metals and non metals refining of metals basics of metallurgy basic metallurgical processes

  1. They are hard

  2. They are impure

  3. They are lustrous

  4. They are malleable

Show answer
Correct Option: B
Explanation:

Refining of metals is required because the metals that have been extracted by concentration of ore are still impure.