QJEEM10Ch7607: JEE Main 2010 Chemistry - Class 12 JEEM10Ch7607 Solution: The Gibbs energy for the decomposition of Al 2 O 3 at 500 o C…

Question

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The Gibbs energy for the decomposition of Al₂O₃ at 500^oC is as follows :

{2 \over 3}A{l_2}{O_3}

\to

{4 \over 3}Al + {O_2}

,

{\Delta _r}G

= + 966 kJ mol^–1

The potential difference needed for electrolytic reduction of Al₂O₃ at 500^oC is at least :

Accepted Answer

\Delta G = - nFE

or

E = {{\Delta G} \over { - nF}} = {{966 \times {{10}^3}} \over {4 \times 36500}}

= - 2.5\,\,V

\therefore

The potential difference needed for the reduction

=2.5

V

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