Tag: chemistry

Questions Related to chemistry

The composition of malachite is:

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

  1. $CuFeS _2$

  2. $CuCO _3$

  3. $CuCO _3.Cu(OH) _2$

  4. $Cu(OH) _2$

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Correct Option: C
Explanation:

The chemical formula of malachite is $Cu _2CO _3(OH) _2$. Hence the composition is $CuCO _3.Cu(OH) _2$.

In the extraction of copper, metal is formed in the Bessemer converter due to a reaction:-

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

  1. ${Cu _2S+2Cu _2O\rightarrow 6Cu+SO _2}$

  2. ${Cu _2S\rightarrow 2Cu+S}$

  3. ${Fe+Cu _2O\rightarrow 2Cu+FeO}$

  4. ${2Cu _2O\rightarrow 4Cu+O _2}$

Show answer
Correct Option: A
Explanation:
In the extraction of copper, metal is formed in the Bessemer converter due to self reduction.

Reaction:
$Cu _2S + 2Cu _2O \longrightarrow 6Cu + SO _2$
The slag obtained during the extraction of copper pyrites is composed mainly of ${ FeSiO } _{ 3 }$.
chemistry general principles of metallurgy extraction of copper and zinc extraction of copper and zinc from their oxides basics of metallurgy

  1. True

  2. False

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Correct Option: A
Explanation:

Copper is mainly extracted from copper pyrites. After the concentration of its ore by froth flotation process, the ore is roasted in a current of air to remove arsenic, antimony and much of sulphur.

The ore is then mixed with a little coke and sand and smelted in a water-jacketed blast furnace. The minor reactions that occured during roasting continue here. Ferrous oxide combines with sand to form a fusible slag.

$FeO + SiO _2 \rightarrow FeSiO _3$ slag

Copper, which is extracted from cuprite, is a/an :

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

  1. sulphide ore

  2. carbonate ore

  3. oxide ore

  4. halide ore

Show answer
Correct Option: C
Explanation:

Cuprite is an oxide mineral composed of copper(II) oxide ($Cu _2O$), and is a minor ore of copper. It can yield small gemstones.

Copper is extracted from the ore copper pyrite by smelting in a blast furnace. The flux used and the slag formed are :

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

  1. flux $CaO$, slag $CaSiO _3$

  2. flux $SiO _2$, slag $CaSiO _3$

  3. flux $FeO$, slag $FeSiO _3$

  4. flux $SiO _2$,slag $FeSiO _3$

Show answer
Correct Option: D
Explanation:

Copper is extracted from the ore copper pyrite by smelting in a blast furnace. The flux used is  $SiO _2$ and slag formed is $FeSiO _3$.

Copper is extracted by the method:

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

  1. Self-reduction

  2. Carbon reduction

  3. Oxidation-reduction

  4. None of these

Show answer
Correct Option: A
Explanation:

Copper is obtained from its one by process of self reduction or intoreduction.
$Cu _2S+2Cu _2O \rightarrow 6Cu+SO _2$

Willemite is

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

  1. $Zn _2SiO _4$

  2. $H _2PtCl _6$

  3. $ZnO$

  4. $ZnOFe _2O _3$

Show answer
Correct Option: A
Explanation:

Chemical formula of willemite is Zn₂SiO₄

Chloroform on reduction with zinc dust and water gives

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

  1. Methyl chloride

  2. Dichloro methane

  3. Chloro methane

  4. Methane

Show answer
Correct Option: D
Explanation:

$\underset{\displaystyle chloroform}{CHCl _3}\overset{\displaystyle 6[H]; Zn/H _2O}{\underset{\underset {\displaystyle -ZnCl _2}{-HCl}}{\displaystyle \rightarrow}}\underset{\displaystyle methane}{CH _4}$.
Chloroform on reduction with Zn and HCl gives dichloromethane $(CH _2Cl _2)$.

Zinc spelter is the purest form of zinc.

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

  1. True

  2. False

Show answer
Correct Option: B
Explanation:

Spelter zinc is an alloy of equal parts copper and zinc, i.e. a brass, used for hard soldering and brazing, or as an alloy, containing lead, that is used instead of bronze.

Hence, it is not the purest form of zinc.

Polling process is employed for the removal of:

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

  1. $Cu _2O\ from \ Cu$

  2. $Al _2O _3\ from\ Al$

  3. $Fe _2O _3\ from\ Fe$

  4. None of the above.

Show answer
Correct Option: A
Explanation:

Polling is a metallurgical method employed in the purification of copper which contains cuprous oxide as an impurity. 

In the past, freshly cut trees were used as wooden poles. The sap in these poles acted as the reducing agent. The heat of the copper makes the pole emit a gas that reduces the cuprous oxide to copper.