Tag: basics of metallurgy

Questions Related to basics of metallurgy

Blister copper obtained during extraction from cuprous oxide is called so because:

chemistry general principles of metallurgy extraction of copper and zinc extraction of copper and zinc from their oxides basics of metallurgy

  1. it has blister like eruptions due to evolution of gas

  2. it has a shining surface like blister

  3. it is the most impure form of copper

  4. its surface is uneven due to different thickness at different place

Show answer
Correct Option: A
Explanation:

The various reaction involved in extraction of copper from cuprous oxide are:
$2FeS+3O _2 \rightarrow 2FeO+2SO _2$
$FeO+SiO _2 \rightarrow FeSiO _3$
$2Cu _2S+3O _2 \rightarrow 2Cu _2O+2SO _2$
$2Cu _2O+Cu _2S \rightarrow 6Cu+SO _2$
The solidified copper obtained has blistered appearance due to the evolution of $SO _2$ and so it is called blister copper.

Why is partial roasting of sulphide ore done in metallurgy of copper?

chemistry general principles of metallurgy extraction of copper and zinc extraction of copper and zinc from their oxides basics of metallurgy

  1. Auto-reduction of $CuO$ formed is carried out by remaining $CuS$ in the reaction.

  2. $Cu$ is separated out by partial reduction due to sedimentation.

  3. Due to difference in gravity $CuO$ and $CuS$ are separated.

  4. Complete roasting cannot be done in one step hence partial roasting is done.

Show answer
Correct Option: A
Explanation:

Partial reduction of Sulphide ores gives copper oxide which further reacts with copper sulphide to show an auto reduction.

$2CuS+3O _2\longrightarrow 2CuO+2SO _2$
$2CuO+CuS\overset {Autoreduction}{\longrightarrow}3Cu+SO _2$

Blister copper is:

chemistry general principles of metallurgy extraction of copper and zinc extraction of copper and zinc from their oxides basics of metallurgy

  1. impure copper

  2. obtained in self-reduction process during bessemerisation

  3. both are correct

  4. none is correct

Show answer
Correct Option: C
Explanation:

Blister copper is a form of a impure copper which is obtained in self reduction process during bessemerization.

Reactions take place in blast furnace-
$2Cu _2O+Cu _2S\longrightarrow 6Cu+SO _2$
The molten metal is cooled in sand moulds $SO _2$ escapes. The impure copper metal is known as "Blister copper" and is about $98\%$ pure.

Following reactions take place during extraction of gold.
$4Au+8CN^-+2H _2O+O _2\rightarrow 4[Au(CN) _2]^-+4OH^-$
$2[Au(CN) _2]^-+Zn\rightarrow 2Au+[Zn(CN) _4]^{2-}$
Zinc in the extraction of gold acts as a/an:

chemistry general principles of metallurgy extraction of copper and zinc extraction of copper and zinc from their oxides basics of metallurgy

  1. oxidising agent

  2. flux

  3. reducing agent

  4. decomposing agent

Show answer
Correct Option: C
Explanation:
$4Au+8CN^-+2H _2O+O _2\longrightarrow 4[Au(CN) _2]^-+4OH^-$
$2[Au(CN) _2]^-+Zn\longrightarrow 2Au+[Zn(CN) _4]^{2-}$
                                 $0$                        $+2$
In the above reaction, Zinc is changing its states from $0$ to $+2$ so zinc is getting oxidized and it acts as reducing agent.

Mark the incorrect statement.

chemistry general principles of metallurgy extraction of copper and zinc extraction of copper and zinc from their oxides basics of metallurgy

  1. Copper is extracted by smelting in a reverberatory furnace.

  2. Zinc is extracted by reduction of oxide with aluminum.

  3. Aluminium is extracted by electrolysis of its oxide.

  4. Iron is extracted by reduction of its oxide in blast furnace.

Show answer
Correct Option: B
Explanation:
It is not profitable method for extraction of Zinc. Zinc is extracted by distillation and by electrolytic refining. So, it is not extracted by reduction of oxide with Aluminium.

Which of the following metals is extracted using a silica lined convertor?

chemistry general principles of metallurgy extraction of copper and zinc extraction of copper and zinc from their oxides basics of metallurgy

  1. $Mg$

  2. $Al$

  3. $Cu$

  4. $Zn$

Show answer
Correct Option: C
Explanation:

During the extraction of copper from cuprous oxide $(copper[I]oxide)$ the ore is heated in a reverberatory furnace after mixing with silica. In the furnace, iron oxide, slag of iron silicate and copper is produced in the form of copper matte. This contains $Cu _2S$ and $FeS$.

$FeO+SiO _2\longrightarrow \underbrace {FeSiO _3} _{(slag)}$
Copper matte is then charged into silica lined converter. Some silica is also added and hot air blast is blown to convert the remaining $FeS _2, FeO$ and $Cu _2S/Cu _2O$ to metallic copper.

Zinc is refined by :

chemistry general principles of metallurgy extraction of copper and zinc extraction of copper and zinc from their oxides basics of metallurgy

  1. Liquation (or) distillation under reduced pressure

  2. Electrolytic method or polling

  3. Liquation or electrolytic method

  4. Distillation under reduced pressure or electrolytic method

Show answer
Correct Option: D
Explanation:

Zinc is refined by distillation under reduced pressure or electrolytic method. Distillation is very useful for low boiling metals like zinc and mercury. The impure metal is evaporated to obtain the pure metal as distillate.

The volatile impurities associated with zinc spelter are _______ .

chemistry general principles of metallurgy extraction of copper and zinc extraction of copper and zinc from their oxides basics of metallurgy

  1. Cd and Fe

  2. Fe and As

  3. Cd and C

  4. Cd and As

Show answer
Correct Option: D
Explanation:

The volatile impurities associated with zinc spelter are Cd and As and the non-volatile impurities are Fe and C.

Choose the odd one out :

chemistry general principles of metallurgy extraction of copper and zinc extraction of copper and zinc from their oxides basics of metallurgy

  1. Steel

  2. Copper

  3. Bronze

  4. Brass

Show answer
Correct Option: B
Explanation:
Copper is pure metal.

But steel, bronze and brass are metal alloy.

Steel is an alloy of iron and carbon, and sometimes other elements.

Brass is an alloy of copper and zinc. 

Bronze is a metal alloy consisting primarily of copper, usually with tin as the main additive, but sometimes with other elements such as phosphorus, manganese, aluminium, or silicon.

Hence, option B is correct.

A brown and bright element 'X' when heated in presence of air turns into black substance 'Y'. If hydrogen gas is passed over this heating material again 'X' is obtained 'X' and 'Y' are -

chemistry general principles of metallurgy extraction of copper and zinc extraction of copper and zinc from their oxides basics of metallurgy

  1. Cu & CuO

  2. S & $SO _2$

  3. C & $CO _2$

  4. Na & NaH

Show answer
Correct Option: A
Explanation:

$2 Cu + O _2\xrightarrow {(\Delta)} 2CuO$
(x)                            (y)
Brown & Bright         Black
$CuO + H _2 \rightarrow Cu + H _2O$