Tag: chemistry

Questions Related to chemistry

In the electrolytic reduction of alumina, the electrolyte is covered with coke powder because, it __________.

chemistry production of metals extraction of aluminium metallurgy of aluminium extraction of metals by electrolysis

  1. prevents oxidation of aluminium formed

  2. reacts with aluminium forming aluminium carbide

  3. prevents heat loss from the electrolyte

  4. none of the above

Show answer
Correct Option: C
Explanation:

The electrolytic mixture is sprinkled with coke to prevent the anode's oxidation by the oxygen evolved

Also, more material to the top of the anode is continuously added in the form of briquettes made from coke and pitch. The lost heat from the smelting operation is used to bake the briquettes into the carbon form required for reaction with alumina.
Therefore, $C$ is correct

A layer of coke is spread over bauxite during extraction of aluminium. This act as a/an

chemistry production of metals extraction of aluminium metallurgy of aluminium extraction of metals by electrolysis

  1. Flux

  2. Slag to remove impurities

  3. Reducing agent

  4. Insulation and doest not allow heat to escape

Show answer
Correct Option: D
Explanation:

To prevent corrosion, coke powder is kept at the top which also prevents escape of heat.

Aluminum is used for making cooking utensils. which of the following propertis of aluminium are responsible for the same ?
(i) Good thermal conductivity ctrical conductivity
(ii) Good electrical conductivity
(iii) Ductillity
(iv) High melting point

chemistry production of metals extraction of aluminium metallurgy of aluminium extraction of metals by electrolysis

  1. (i) and (ii)

  2. (i) and (iii)

  3. (ii) and (iii)

  4. (i) and (iv)

Show answer
Correct Option: D
Explanation:

Aluminium is used for making cooking utensils,the properties used.

(1)Good thermal conductivity & electrical conductivity.
Thermal conductivity good implies laser cooking and saves time.
(ii)Malleable property chelps it to easily shape into utensils.
(iii)High melting point would ensure utensils don't melt on cooking temperature.

The mass of carbon anode consumed (giving of carbon dioxide) in the production of $270 \ kg$ aluminium metal bum bauxite by Hall process is: (Atomic mass $Al = 27$)

chemistry production of metals extraction of aluminium metallurgy of aluminium extraction of metals by electrolysis

  1. $180$ kg

  2. $270$ kg

  3. $540$ kg

  4. $90$ kg

Show answer
Correct Option: D
Explanation:

The chemical reaction for the Hall process is given by

$2Al _2O _3+3C\rightarrow 4Al+3CO _2$
Moles of aluminium produced$=\dfrac{270000}{27}=10000$
According to the reaction,
$10000 \; kg$ moles of aluminium can be produced by consuming $2500\times3=7500 \ moles $ of Carbon
Hence mass of carbon=$12\times 7500=90000\ g=90\ kg$

Therefore, D is the correct answer

In case of Hall's process applied on reduction of $Al _2O _3$ to Al can be done by using:

chemistry production of metals extraction of aluminium metallurgy of aluminium extraction of metals by electrolysis

  1. Cathode - Al, Anode - Graphite

  2. Cathode - Graphite, Anode - Graphite

  3. Cathode - Graphite, Anode - Steel

  4. Cathode - Steel, Anode - Graphite

Show answer
Correct Option: B
Explanation:

Both are graphite 

since in Hall's Process both the terminals are carbon content.

Function of adding cryolite in the extraction of aluminium from pure alumina is?

chemistry production of metals extraction of aluminium metallurgy of aluminium extraction of metals by electrolysis

  1. to increase the fusion temperature

  2. to decrease the conductivity of alumina

  3. to decrease the fusion temperature and increase the electrical conductivity

  4. none of these

Show answer
Correct Option: C
Explanation:

As Alumina has high melting point and low conductivity, Cryolite is added to reduce melting point and flour spar is added in small amount to increase electrical conductivity. 

Aluminium is extracted by the electrolysis of:

chemistry production of metals extraction of aluminium metallurgy of aluminium extraction of metals by electrolysis

  1. Bauxite

  2. Alumina

  3. Alumina mixed with molten cryolite

  4. Molten cryolite

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Correct Option: C
Explanation:

In the extraction of aluminium by electrolytic process alumina $Al _2O _3$ is used along with molten fluorspar and cryolite.


Hence, the correct option is $C$

Which of the following is / are involved in extraction of aluminium from bauxite?

chemistry production of metals extraction of aluminium metallurgy of aluminium extraction of metals by electrolysis

  1. Electrolytic reduction

  2. Leaching

  3. Hyfrolysis

  4. Thermal decomposition

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Correct Option: A

Aluminium is obtained by.

chemistry production of metals extraction of aluminium metallurgy of aluminium extraction of metals by electrolysis

  1. heating AL2O with iron

  2. heating AL2O3 with coke

  3. electrolysing a solution of AL2O3 in molten cryolite

  4. electrolysing fused AICI3

Show answer
Correct Option: D

All the statements are correct.
(i) In gold Schmidt thermite process aluminium acts as a reducing agent
(ii) Mg is extracted by electrolysis of aq. solution of $MgCl _{2}$
(iii) Extraction of Pb is possible by smelting
(iv) Red bauxite is purified by Serpeck's  Method

chemistry production of metals extraction of aluminium metallurgy of aluminium extraction of metals by electrolysis

  1. True

  2. False

Show answer
Correct Option: A
Explanation:

Option A & C are correct.
But Serpeck's  Method is used to purify white bauxite.
and
Mg is extracted by electrolysis of anhydrous $MgCl _{2}$.