Tag: basics of metallurgy

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Multiple choice chemistry principles and processes of isolation of elements refining of metals basics of metallurgy basic metallurgical processes

Extraction of metal from the ore cassiterite involves

  1. carbon reduction of an oxide ore

  2. self- reduction of an sulphide ore

  3. removal of iron impurity

  4. both A and C
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Tin is obtained by reducing the ore cassiterite with coal in a reverberatory furnace; limestone is added to produce a slag with impurities, which can be removed.

$SnO _2  +  2C \longrightarrow Sn + 2 CO$.

Crude tin so obtained is contaminated with iron, lead, and other metals. It is, therefore, remelted on an inclined furnace. The process is called liquation. The easily fusible tin metals away and the less fusible impurities are left behind. Molten tin is finally stirred with green poles of wood in contact with air. In this process, any remaining metal impurities are oxidized forming a scum, which rises to the surface and is removed. This process is called polling.

Multiple choice chemistry principles and processes of isolation of elements refining of metals basics of metallurgy basic metallurgical processes

Which are correctly matched?

  1. Poling-refining of copper

  2. Cupellation- refining of silver

  3. Smelting-An oxidation process

  4. Roasting-An oxidation process
Reveal answer Fill a bubble to check yourself
A,B,D Correct answer
Explanation

A) Poling is a method employed in the purification of copper which contains cuprous oxide as an impurity.correct.
B) Cupellation is a refining process in metallurgy, where ores or alloyed metals are treated under high temperatures and controlled operations to separate gold and silver, from lead, copper, zinc, arsenic, antimony or bismuth.correct.
C) The process of extracting a metal from its oxide is known as 'smelting'. Most smelting processes involve direct reduction of the ore by carbon to metal and carbon dioxide. The production of primary aluminium is a good example of such a process. Its not oxidation.wrong
D) Roasting is a step of the processing of certain ores More specifically, roasting is a metallurgical process involving gassolid reactions at elevated temperatures with the goal of purifying the metal component(s). During roasting, the sulfide is converted to an oxide, and sulfur is released as sulfurdioxide, a gas.$2Cu _2S + 3O _2\rightarrow  2 Cu _2O + 2 SO _2$.correct.
options A,B & D are correct.

Multiple choice chemistry principles and processes of isolation of elements refining of metals basics of metallurgy basic metallurgical processes

In Poling process, Hydrocarbon gases escaping from the poles act as _____ agents.

  1. reducing

  2. oxidation

  3. both

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

Poling is a process in which the impure metal containing oxide as impurities is purified. It is melted and stirred with green poles of wood. Hydrocarbon gases escaping from the poles act as reducing agents and reduce the oxide impurities e.g., impurity of Cu$ _2$O which is reduced to metallic copper by poling.
$Cu _2O + CO \rightarrow 2Cu + CO _2 \uparrow$
$Cu _2O + H _2 \rightarrow 2Cu + H _2O$

Multiple choice chemistry principles and processes of isolation of elements refining of metals basics of metallurgy basic metallurgical processes

In polling, wood gas is responsible for the removal of volatile impurities.

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

True. Polling is used for converting Copper Oxide $(Cu _2O)$ to Copper $(Cu)$. When ore is heated with wood poles, the poles release charcoal, shoot and gas. The gas released reduces $CuO$ to $Cu$. So the gas takes away impurities. 

Multiple choice chemistry principles and processes of isolation of elements refining of metals basics of metallurgy basic metallurgical processes

Which of the following methods is used to remove lead present in silver ?

  1. Cupellation

  2. Distillation

  3. Poling

  4. Lavigation
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Cupellation is a process of separation of gold or silver from impurities by melting the impure metal in a cupel (a flat porous dish made of refractory or high-temperature resistant material  ) and then directing a blast of hot air on it in a special furnace. The impurities, including lead,copper, tin, and other unwanted metals, are oxidized and partly vaporized and partly absorbed into the pores of the cupel.

Multiple choice chemistry principles and processes of isolation of elements refining of metals basics of metallurgy basic metallurgical processes

Poling process:

  1. reduces $SnO _2$ to Sn

  2. oxidizes impurities like iron and removes as scum

  3. uses green poles

  4. uses brown poles
Reveal answer Fill a bubble to check yourself
A,B,C Correct answer
Explanation

Poling: A refining process of crude metal for removing metal oxide impurities by stirring molten metal in a ladle with a pole of green wood (poles).


In the poling process, the reduction of oxides to metal atom will be done.

Ex: Extraction of copper from copper oxide and Sn from $SnO _2$.

Hence options A,B & C are correct.

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

Which of the following sulphides when  heated strongly in air gives the corresponding metal without undergoing separate reduction of oxide?

  1. $Cu _2S$
  2. $FeS$
  3. $HgS$
  4. $ZnS$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

$2Cu _2S+3O _2\longrightarrow 2Cu _2O+2SO _2$

$2ZnS+3O _2\longrightarrow 2ZnO+2SO _2$
$2PbS+3O _2\longrightarrow 2PbO+2SO _2$
$2HgS+3O _2\longrightarrow 2HgO+2SO _2$
$FeS+O _2\longrightarrow Fe+SO _2$
$FeS$ when heated directly in air gives $Fe$. 

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

Which of the following reactions show the process of smelting?

  1. $2PbO + PbS \rightarrow 3Pb + SO _2$
  2. $2Na[Au(CN) _2]+Zn \rightarrow Na _2[Zn(CN) _4]+2Au$
  3. $PbO+C\rightarrow Pb + CO$
  4. $2HgS + 3O _2\rightarrow 2HgO+2SO _2$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Carbon reduction occurs in smelting from oxide ore. $PbO+C\longrightarrow Pb+CO$

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

Fill in the blanks with the correct choice.
The undesired impurities present in the ores are called (i). To remove the volatile impurities from the ore, the (ii) process is carried out. Flux combines with non-fusible impurities to form (iii). $CaO$ acts as a (iv) flux.

  1. (i) - gangue, (ii) -roasting, (iii) - slag, (iv) -acidic

  2. (i) - gangue, (ii) - calcination, (iii) - slag, (iv) - basic

  3. (i) - anode mud, (ii) - leaching, (iii) - matrix, (iv) -acidic

  4. (i) - gangue, (ii) -roasting, (iii) - solution, (iv) -acidic
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
$(i)$ The undesired impurities present in the ores are called gangue.
$(ii)$ To remove the volatile impurities from the ore calcination is carried out.
$(iii)$ Flux combines with non-fusible impurities to form slag.
$(iv)$ $CaO$ acts as basic flux.
Multiple choice chemistry production of metals extraction of metal from concentrated ore basics of metallurgy extraction of metals from ore

Extraction of chlorine from brine is based on:

  1. reduction

  2. displacement

  3. oxidation

  4. evaporation
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
In the extraction of chlorine by electrolysis of brine, oxidation of ${ Cl }^{ - }$ ion to chlorine gas occurs.
$2{ Cl }^{ - }+2{ H } _{ 2 }O\rightarrow 2{ OH }^{ - }+{ H } _{ 2 }+{ Cl } _{ 2 }$