Class 12 Chemistry - Chapter General Principles and Processes of Isolation of Elements NCERT Solutions | The reaction, Cr
The reaction,
Cr2O3 + 2Al → Al2O3 + 2Cr (ΔGo = -421kJ)
is thermodynamically feasible as is apparent from the Gibbs energy value. Why does it not take place at room temperature?
The change in Gibbs energy is related to the equilibrium constant, K as
ΔG = - RT in K
At room temperature, all reactants and products of the given reaction are in the solid state. As a result, equilibrium does not exist between the reactants and the products. Hence, the reaction does not take place at room temperature. However, at a higher temperature, chromium melts and the reaction takes place.
We also know that according to the equation,
ΔG = ΔH - TΔS
Increasing the temperature increases the value of TΔS, making the value of ΔG more and more negative. Therefore, the reaction becomes more and more feasible as the temperature is increased.
More Questions From Class 12 Chemistry - Chapter General Principles and Processes of Isolation of Elements
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Write down the reactions taking place in different zones in the blast furnace during the extraction of iron.
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Copper can be extracted by hydrometallurgy but not zinc. Explain.
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Outline the principles of refining of metals by the following methods:
(i) Zone refining
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(iii) Vapour phase refining
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Name the common elements present in the anode mud in electrolytic refining of copper. Why are they so present ?
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Write chemical reactions taking place in the extraction of zinc from zinc blende.
- Q:-
Describe a method for refining nickel.
- Q:-
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Popular Questions of Class 12 Chemistry
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For the reaction R → P, the concentration of a reactant changes from 0.03 M to 0.02 M in 25 minutes. Calculate the average rate of reaction using units of time both in minutes and seconds.
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Write the formulas for the following coordination compounds:
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(iii) Tris(ethane-1,2-diamine) chromium(III) chloride
(iv) Amminebromidochloridonitrito-N-platinate(II)
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(iv) 4-Oxopentanal
(v) Di-sec-butyl ketone
(vi) 4-Fluoroacetophenone
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Write structures of the following compounds:
(i) 2-Chloro-3-methylpentane
(ii) 1-Chloro-4-ethylcyclohexane
(iii) 4-tert. Butyl-3-iodoheptane
(iv) 1,4-Dibromobut-2-ene
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Further show:
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