Home
Class 12
CHEMISTRY
Assertion : Magnesium metal is not used ...

Assertion : Magnesium metal is not used for the reduction of alumina in the metallurgy of aluminium.
Reason : `MgO` curve lies above `Al_(2)O_(3)` curve in Ellingham diagram.

A

If both assertion and reason are true and reason is the correct explanation of assertion .

B

if both assertion and reason are true but reason is not the correct explanation of assertion

C

If assertion is true but reason is false

D

If both assertion and reason are false.

Text Solution

Verified by Experts

The correct Answer is:
C
The curve for MgO lies below `Al_(2)O_(3)` in Ellingham diagram for an appreciable range of temperature and in that temperature range magnesium can reduce `Al_(2)O_(3)` , but this process is uneconomical hence, it is not used to reduce alumina.
Promotional Banner

Topper's Solved these Questions

  • GENERAL PRINCIPLES AND PROCESSES OF ISOLATION OF ELEMENTS

    NCERT FINGERTIPS ENGLISH|Exercise Occurrence Of Metals|13 Videos

  • GENERAL PRINCIPLES AND PROCESSES OF ISOLATION OF ELEMENTS

    NCERT FINGERTIPS ENGLISH|Exercise Concentration Of Ores|17 Videos

  • GENERAL PRINCIPLES AND PROCESSES OF ISOLATION OF ELEMENTS

    NCERT FINGERTIPS ENGLISH|Exercise NCERT EXEMPLAR PROBLEMS|13 Videos

  • ELECTROCHEMISTRY

    NCERT FINGERTIPS ENGLISH|Exercise Assertion And Reason|15 Videos

  • HALOALKANES AND HALOARENES

    NCERT FINGERTIPS ENGLISH|Exercise NCERT Exemplar|27 Videos

Similar Questions

Explore conceptually related problems

Although thermodynamically feasible, in practice, magnesium metal is not used for the reduction of alumina in the metallurgy of aluminium. Why ?

Assertion : In the electrolytic reduction of Al_(2)O_(3) , cryolite is used. Reason : Cryolite is an ore of aluminium.

Explain the following (i) Excess of carbon is added to zinc metallurgy. (ii) In the elctrolysis of alumina, cryolite is added to alumina. (iii) Coke does not cause reduction of Al_(2)O_(3) . (iv) Gold is soluble in aquaregia, silver is not.

What role is played by CO_(2) in getting pure alumina (Al_(2)O_(3)) in the extraction of aluminium ?

Aluminium is obtained from Al_(2)O_(3) by _____reduction.

When aluminium oxide (Al_(2)O_(3)) is electrolysed for the production of aluminium metal. For a given quantity of electricty, the number of moles of aluminium obtained if the volume of O_(2) gas obtained is 201.6 litre measured at NTP, is

For a sponaneous reaction, the free energy change must be negative, Delta G=Delta H-T Delta S, Delta H is the enthalpy change during the reaction. T is the absolute temperature, and Delta S is the change in entropy during the reaction. Consider a reaction such as the formation of an oxide M+O_(2) to MO Dioxygen is used up in the course of this reaction. Gases have a more random structure (less ordered) than liquid or solids. Consequently gases have a higher entropy than liquids and solids. In this reaction S (entropy or randomness) decreases, hence Delta S is negative. Thus, if the temperature is raised then T Delta S becomes more negative,Since, TDelta S is substracted in the equation, then Delta G becomes less negative. Thus, the free energy change increases with the increase in temperature. The free energy changes that occur when one mole of common reactant (in this case dioxygen) is used may be plotted graphically aginst temperature for a number of reactions of metals to their oxides. The following plot is called an Ellingham diagram for metal oxide. Understanding of Ellingham diagram is extremely important for the efficient extraction of metals. Free energy change of Hg and Mg for the convertion to oxides the slpe of Delta G vsT has been changed above the boiling points of the given metal because :

For a sponaneous reaction, the free energy change must be negative, Delta G=Delta H-T Delta S, Delta H is the enthalpy change during the reaction. T is the absolute temperature, and Delta S is the change in entropy during the reaction. Consider a reaction such as the formation of an oxide M+O_(2) to MO Dioxygen is used up in the course of this reaction. Gases have a more random structure (less ordered) than liquid or solids. Consequently gases have a higher entropy than liquids and solids. In this reaction S (entropy or randomness) decreases, hence Delta S is negative. Thus, if the temperature is raised then T Delta S becomes more negative,Since, TDelta S is substracted in the equation, then Delta G becomes less negative. Thus, the free energy change increases with the increase in temperature. The free energy changes that occur when one mole of common reactant (in this case dioxygen) is used may be plotted graphically aginst temperature for a number of reactions of metals to their oxides. The following plot is called an Ellingham diagram for metal oxide. Understanding of Ellingham diagram is extremely important for the efficient extraction of metals. Which of the following elements can be prepared by heating the oxide above 400^(@)C ?

For a sponaneous reaction, the free energy change must be negative, Delta G=Delta H-T Delta S, Delta H is the enthalpy change during the reaction. T is the absolute temperature, and Delta S is the change in entropy during the reaction. Consider a reaction such as the formation of an oxide M+O_(2) to MO Dioxygen is used up in the course of this reaction. Gases have a more random structure (less ordered) than liquid or solids. Consequently gases have a higher entropy than liquids and solids. In this reaction S (entropy or randomness) decreases, hence Delta S is negative. Thus, if the temperature is raised then T Delta S becomes more negative,Since, TDelta S is substracted in the equation, then Delta G becomes less negative. Thus, the free energy change increases with the increase in temperature. The free energy changes that occur when one mole of common reactant (in this case dioxygen) is used may be plotted graphically aginst temperature for a number of reactions of metals to their oxides. The following plot is called an Ellingham diagram for metal oxide. Understanding of Ellingham diagram is extremely important for the efficient extraction of metals. For the conversion of Ca(s) to Ca(s) which of the following represent the Delta G vs. T ?

Assertion : Although aluminium is above hydrogen in electrochemical series, it is stable in air and water. Reason : The thin protective layer of oxide (AI_(2) O_(3)) on the surface protects the aluminium.