Home
Class 12
CHEMISTRY
The value of Delta(f)G^(@) for formation...

The value of `Delta_(f)G^(@)` for formation `Cr_(2)O_(3)` is `-540` kJ `mol^(-1)` and that of `Al_(2)O_(3)` is `-827` kJ `mol^(-1)`. Is the reduction of `Cr_(2)O_(3)` possible with aluminium?

Text Solution

Verified by Experts

The two equations are :
`(4)/(3)Al_((s))+O_(2(g))rarr(2)/(3)Al_(2)O_(3(s))`
`Delta_(f)G^(@)=-827kJmol^(-1)" "...(i)`
`(4)/(3)Cr_((s))+O_(2(g))rarr(2)/(3)Cr_(2)O_(3(s))`
`Delta_(f)G^(@)=-540kJmol^(-1)" "...(ii)`
Subtracting equation (ii) from equation (i), we get
`(4)/(3)Al(s)+(2)/(3)Cr_(2)O_(3)(s)rarr(2)/(3)Al_(2)O_(3)(s)+(4)/(3)Cr(s)`,
`Delta_(f)G^(@)=-287kJmol^(-1)`
As `Delta_(f)G^(@)` of the combined redox reaction is negative, therefore, reduction of `Cr_(2)O_(3)` by Al is possible.
Promotional Banner

Topper's Solved these Questions

  • GENERAL PRINCIPLES AND PROCESSES OF ISOLATION OF ELEMENTS

    OSWAAL PUBLICATION|Exercise TOPIC 2 (LONG ANSWER TYPE QUESTIONS-II)|2 Videos

  • GENERAL PRINCIPLES AND PROCESSES OF ISOLATION OF ELEMENTS

    OSWAAL PUBLICATION|Exercise TOPIC 2 (SHORT ANSWER TYPE QUESTION-I)|15 Videos

  • ELECTRO-CHEMISTRY

    OSWAAL PUBLICATION|Exercise Topic - 3 ELECTROLYSIS , LAWS OF ELECTROLYSIS, BATTERIES, FUEL CELLS AND CORROSION (LONG ANSWER TYPE QUESTIONS)|4 Videos

  • HALOALKANES & HALOARENES

    OSWAAL PUBLICATION|Exercise Topic 2 (Properties of Haloarenes and Haloalkanes) (Long Answer Type Questions - II)|1 Videos

Similar Questions

Explore conceptually related problems

When compared to DeltaG^(@) for the formation of Al_(2)O_(3), the DeltaG^(@) for the formation of Cr_(2)O_(3) is

In Cr_(2)O_(7)^(2-) :

The heat of formation of Fe_(2)O_(3) is -824.2 kJ mol^(-1). Delta H for the reaction 2Fe_(2)O_(3)(s)rarr 4Fe(s)+3O_(2)(g) is :

Delta_(f)U^(@) of formation of CH_(4)(g) at certain temperature is - 393 kJ mol^(-1) . The value of Delta_(f)H^(@)

The enthalpy of the reaction : H_(2)O_(2)(l) rarr H_(2)O(l) + (1)/(2)O_(2)(g) is -98.3 KJ mol^(-1) and the enthalpy of formation of H_(2)O(l) is -285.6 kJ mol^(-1) . The enthalpy of formation of H_(2)O_(2)(l) is :

The standard enthalpy of formation of NH_(3) is - 46.0 kJ mol^(-1) . If the enthalpy of formation of H_(2) from its atoms is - 436 kJ mol^(-1) and that of N_(2) is - 712 kJ mol^(-1) , the average bond enthalpy of N - H bond is NH_(3) is

If Delta_(f)G^(@) for NH_(3)(g) is - 16.4 kJ mol^(-1) , then Delta G^(@) for the reaction : N_(2)(g) + 3 H_(2)(g) rarr 2NH_(3)(g) is

The enthalpy of vaporisation for water is 41.2 kJ mol^(-1), DeltaH for the reaction 2H_2O(g) to 2H_2O(l) is :