Tag: basics of metallurgy

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Multiple choice chemistry production of metals extraction of metal from concentrated ore basics of metallurgy extraction of metals from ore

In which of the following chemical leaching is used either in the extraction of metal or in the concentration of ore?

  1. Argentite

  2. Bauxite

  3. Alluvial sand containing gold

  4. All of these
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Chemical leaching is used in the extraction of silver from Argentite (Ag2S) using sodium cyanide solution.

Multiple choice chemistry production of metals extraction of metal from concentrated ore basics of metallurgy extraction of metals from ore

Which one of the following statements is incorrect about rock salt type?

  1. It has fcc arrangement of $\mathrm { Na } ^ { + }$
  2. Nat and Cl-ions have a co-ordination number of $6:6$
  3. A unit cell of $NaCl$ consists of four $NaCl$ units

  4. All halides of alkali metals have rock-salt type structure
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The alkali halides crystallize in the NaCl structure also known as rock-salt structure (rock salt is the mineral form of sodium chloride); exceptions being CsCl, CsBr, and CsI, which crystallize in the CsCl structure. In the NaCl structure (face-centered cubic lattice), each cation is surrounding by six anions, and vice versa (coordination number of 6). In the CsCl structure, each cation is surrounded by eight anions and vice versa (coordination number of 8).

Option D is incorrect

Multiple choice chemistry production of metals extraction of metal from concentrated ore basics of metallurgy extraction of metals from ore

The extraction of metals from oxide ores may involve:

  1. reduction with carbon

  2. reduction with aluminium

  3. electrolyte reduction

  4. reduction with CO
Reveal answer Fill a bubble to check yourself
A,B,C,D Correct answer
Explanation

These are the methods for extraction of metals from oxide ores:
Carbon reduction, involving reduction with CO or C
Self reduction
Thermite reduction, which employs Al
Electrolytic reduction.

Multiple choice chemistry production of metals extraction of metal from concentrated ore basics of metallurgy extraction of metals from ore

The advantage(s) of using carbon to reduced a number of oxides and other compounds are :

  1. easy availability of coke.

  2. low cost of carbon.

  3. tendency of carbon to show catenation..

  4. presence of carbon lowers the melting point of the oxide.
Reveal answer Fill a bubble to check yourself
A,B Correct answer
Explanation

The advantage(s) of using carbon to reduced a number of oxides and other compounds are
 (i) easy availability of coke.
 (ii) low cost of carbon.
 (iii) exothermic nature of reaction which requires less energy to keep the furnace hot.


Hence, A and B are the correct options. 

Multiple choice chemistry production of metals extraction of metal from concentrated ore basics of metallurgy extraction of metals from ore

The extraction of metals from oxide ores involve :

  1. reduction with carbon

  2. reduction with aluminium

  3. electrolyte reduction
  4. reduction with $CO$
Reveal answer Fill a bubble to check yourself
A,B,C,D Correct answer
Explanation

During extraction of metals from oxide ores, the reduction of metal ore to crude metal can be carried out by using several methods such as pyrometallurgy, hydrometallurgy and electrometallurgy. Various reducing agents such as carbon, hydrogen, aluminum or other metals can be used. CO also reduces metal ores to crude metals.

Multiple choice chemistry production of metals extraction of metal from concentrated ore basics of metallurgy extraction of metals from ore

Aluminothermy used for the spot welding of large iron structures is based upon the fact that :

  1. As compared to iron, aluminium has greater affinity for oxygen.

  2. As compared to aluminium, iron has greater affinity for oxygen.

  3. Reaction between aluminium and oxygen is endothermic..

  4. Reaction between iron oxide and aluminium is exothermic.
Reveal answer Fill a bubble to check yourself
A,D Correct answer
Explanation

Aluminothermy used for the spot welding of large iron structures is based upon two facts 
(i) As compared to iron, aluminum has greater affinity for oxygen. hence, aluminum acts are reducing agent.
(ii) Reaction between iron oxide and aluminum is exothermic. High temperature is involved in the reaction.
Aluminum reduces iron oxide to iron. 

$Fe _2O _3 + 2 Al \rightarrow 2 Fe + Al _2O _3$

Multiple choice chemistry production of metals extraction of metal from concentrated ore basics of metallurgy extraction of metals from ore

Oxides of the various metals are converted into metal by heating but not in :

  1. $Ag _2O$

  2. CuO

  3. HgO

  4. all are correct
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Oxides of various metal oxides are converted into metals on heating but CuO (copper oxide) does not not converted into metal on heating but by reaction with Cu2S.

CuO + Heat$ \rightarrow$ no reaction
So, answer is B.

Multiple choice chemistry production of metals extraction of metal from concentrated ore basics of metallurgy extraction of metals from ore

The methods chiefly used for the extraction of lead and tin from their ores are respectively _________________.

  1. self reduction and carbon reduction

  2. self reduction and electrolytic reduction

  3. carbon reduction and self reduction

  4. cyanide process and carbon reduction
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The methods chiefly used for the extraction of lead and tin from their ores are respectively self reduction and carbon reduction. Self reduction for lead is as follows.
$2PbS+3O _2 \rightarrow 2PbO+2SO _2 \uparrow$
$PbS+2O _2 \rightarrow PbSO _4$
$2PbO + PbS \rightarrow 3Pb+SO _2 \uparrow$
$PbSO _4+PbS \rightarrow 2Pb+2SO _2 \uparrow$
Carbon reduction for tin is as follows.
$SnO _2+2C \rightarrow Sn+2CO \uparrow$

Multiple choice chemistry production of metals extraction of metal from concentrated ore basics of metallurgy extraction of metals from ore

Which will not give metal on heating ?

  1. $Ag _2CO _3$
  2. $ZnCO _3$
  3. $HgO$
  4. $CuO$
Reveal answer Fill a bubble to check yourself
B,D Correct answer
Explanation
A) $Ag _2CO _3(s)\rightarrow 2Ag(s) + CO _2(g) + O _2(g)$ on heating gives Ag(metal).
B) $ZnCO _3(s)\rightarrow ZnO(s) + CO _2(g)$ on heating  do not give metal it gives ZnO(zinc oxide).
C) $2HgO(heat)\rightarrow 2 Hg + O _2$ on heating gives Hg(metal).
D) CuO when heated in presence of sulfuric acid it also gives CuO again, hence CuO on heating do not give metal.
Hence option B and D are correct.