Tag: thermodynamic principles of metallurgy

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Multiple choice thermodynamic principles of metallurgy general principles and processes of isolation of elements metallurgy chemistry

Which of the following oxides cannot be reduced by coke?

  1. $Cu _2O,\: K _2O$
  2. $Fe _2O,\: ZnO$
  3. $CaO, \: K _2O$
  4. $PbO,\: Fe _3O _4$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Oxides of strong elecropositive metals such as $K, Ca, Na, Al$ and $Mg$ are very stable. It is difficult to reduce them into metallic state by carbon reduction.
Such metals are extracted by passing electricity through their fused chlorides/oxides/hydroxides.

Multiple choice thermodynamic principles of metallurgy general principles and processes of isolation of elements metallurgy chemistry

Which of the following is not correctly matched?

  1. Red bauxite - Purification by Serpeck's method

  2. Iron from haematite - Carbon monoxide reduction

  3. Calamine - Carbonate ore
  4. $FeSiO _3$ - Slag obtained in the extraction of copper
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Red bauxite is purified by Bayer's process, not Serpeck's method. Serpeck's method is typically used for the purification of white bauxite (containing silica as impurity).

Multiple choice thermodynamic principles of metallurgy general principles and processes of isolation of elements metallurgy chemistry

Which one of the following is not a method of concentration of ore? 

  1. Electromagnetic separation

  2. Smelting

  3. Gravity separation

  4. Froth floatation process
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The process of removal of unwanted materials from the ore is known as ore concentration. 


Froth floatation, electromagnetic separation, and gravity separation are few of the processes used for ore concentration.

 
Smelting, however, is a process of heating the ore in order to extract the base metal. 


Hence B is the correct answer

Multiple choice thermodynamic principles of metallurgy general principles and processes of isolation of elements metallurgy chemistry

Name the substance which remains in a test tube after heating ferrous sulphate.

  1. $Fe _2O _3$
  2. $Fe _2S$
  3. $Fe _2(SO _4) _3$

  4. None of these
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Heating farrow sulfate in a test tube following reaction takes place

$FeSO _4.7H _2O\rightarrow Fe SO _4+7H _2O$
$2Fe SO _4\rightarrow Fe _2O _3+SO _2+SO _3$
Both $SO _2$ and $SO _3$ are gases that colorless and evolved out 
Only $Fe _2O _3$  that is ferric oxide which reddish brown in colour remained in the fort tube ,so the answer is $Fe _2O _3$ that is ferric oxide

Multiple choice thermodynamic principles of metallurgy general principles and processes of isolation of elements metallurgy chemistry

Heating mixture of $Cu _2O$ and $Cu _2S$ will give:

  1. $Cu+SO _2$
  2. $Cu+SO _3$
  3. $CuO+CuS$
  4. $Cu _2O+S$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Reaction of the process:


$ 2Cu _2 O+ Cu _2S \overset{\Delta}{\longrightarrow} 6Cu+SO _2$

The heating mixture of Cu$ _2$O and Cu$ _2$S will give Cu and SO$ _2$ mixture.

Hence, the correct option is $A$

Multiple choice thermodynamic principles of metallurgy general principles and processes of isolation of elements metallurgy chemistry

In extractive metallurgy of zinc partial fusion of ZnO with coke is called ______ and reduction of the ore to the molten metal is called________ .

  1. sintering, smelting

  2. roasting, smelting

  3. sintering, roasting

  4. none of these
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Sintering is the process of forming a solid mass of material by heat and/or pressure without melting it to the point of liquefaction. Sintering happens naturally in mineral deposits or as a manufacturing process used with metals, ceramics, plastics, and other materials.

Smeltings main use is to produce a metal from its ore. Smelting uses heat and a chemical reducing agent to decompose the ore, driving off other elements as gasses or slag and leaving just the metal behind. The reducing agent is commonly a source of carbon.The carbon removes oxygen from the ore, leaving behind elemental metal. 

Multiple choice thermodynamic principles of metallurgy general principles and processes of isolation of elements metallurgy chemistry

Carbon reduction method is employed for commercial extraction of :

  1. haematite

  2. cassiterite

  3. iron pyrite

  4. corundum
Reveal answer Fill a bubble to check yourself
A,B Correct answer
Explanation

In extraction of tin from cassiterite-
$SnO _2+2C\rightarrow Sn+2CO$

In extraction of iron from haematite -
$Fe _2O _3+3CO\rightarrow 2Fe+3CO _2$

Iron pyrite $FeS _2$ is a sulphide ore for which froth floatation method is used.
Corundum is a crystalline form of aluminium oxide $Al _2O _3$ with traces of iron, titanium and chromium; for which electrolytic reduction method is used.

Multiple choice thermodynamic principles of metallurgy general principles and processes of isolation of elements metallurgy chemistry

Highly electropositive metals cannot be extracted by carbon reduction process because, these:

  1. metals combine with carbon to form carbides

  2. metals do not react with carbon

  3. metal oxides are not reduced by carbon

  4. loss of metal is more in vaporisation
Reveal answer Fill a bubble to check yourself
A,D Correct answer
Explanation

Highly electropositive metals cannot be extracted by carbon reduction process because of two reasons
(i) Metals combine with carbon to form carbides.
(ii) Loss of metal is more in vaporization.