Tag: refining of metals

Questions Related to refining of metals

Zirconium is purified by 

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

  1. Liquidation

  2. Electrolytic process

  3. Van Arkel method

  4. Calcination

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Correct Option: C

(a) Mond process       (1) Ni
(b) Van-Arkel              (2) Zr
(c) Liquation               (3) Ga
(d)Zone refining         (4) Sn
Correct option is:

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

  1. $a-(1)$ $ b-(2)$ $c-(2)$ $d-(4)$

  2. $a-(1)$ $b-(2) $ $c-(4)$ $d-(3)$

  3. $a-(3)$ $b-(2)$ $c-(4)$ $d-(1)$

  4. $a-(2)$ $b-(3)$ $c-(4)$ $d-(1)$

Show answer
Correct Option: B
Explanation:
Solution:- (B) $a-(1)$ $b-(2) $ $c-(4)$ $d-(3)$
(a) Mond process     $ \Rightarrow$ Ni
(b) Van-Arkel            $ \Rightarrow$ Zr
(c) Liquation             $ \Rightarrow$ Sn
(d)Zone refining       $ \Rightarrow$ Ga

An insoluble substance or mixture that collects at the anode in an electrolytic refining or plating process is known as anode mud.

State True or False.

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

  1. True

  2. False

  3. Cannot be determined

  4. None of the above

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Correct Option: A
Explanation:

Anode mud is the insoluble impurity which settles down at the bottom of the anode during electrolytic refining. The soluble impurities go into the solution.

So the given statement is correct
Hence option $A$ is correct.

Gold is extracted by hydrometallurgical process, based on its property:

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

  1. of being electropositive

  2. of being less reactive

  3. to form complex which are water soluble

  4. to form salt which are water soluble

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Correct Option: C
Explanation:
Hydrometallurgy is a method for obtaining metals from their ores. It is a technique within the field of extractive metallurgy involving the use of aqueous chemistry for the recovery of metals from ores, concentrates, and recycled or residual materials. Gold is extracted by hydrometallurgical process, based on its property to form complexes which are water soluble.

$4Au(s)+8CN^- +O _2(g)+2H _2O\rightarrow \underset{soluble \, complex}{4[Au(CN) _2]^-} + 4OH^-$

Which of the following is true for electrolytic refining?

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

  1. Pure metal is anode and impure metal is cathode

  2. Pure metal is cathode and impure metal is anode

  3. Both are anode

  4. Both are cathode

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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.

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

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

  1. Mond process

  2. Van Arkel process

  3. Liquation

  4. All of the above

Show answer
Correct Option: D
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.

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)