Question: The Gibb’s energy for the decomposition of $Al_{2}O_{3}$ at $500ºC$ is as follows: \[2/3Al_{2}O...

Question

The Gibb’s energy for the decomposition of $Al_{2}O_{3}$ at $500ºC$ is as follows:

$2/3Al_{2}O_{3} \rightarrow 4/3Al + O_{2};\Delta_{r}G = + 966kJ/mol$

The potential difference needed for electrolytic reduction of $Al_{2}O_{3}$ at $500ºC$ is at least

Answer 1

The ionic reactions are :

$2/3 \times (2Al^{3 +}) + 4e^{-} \rightarrow 4/3Al$

$2/3 \times (3O^{2 -}) \rightarrow O_{2} + 4e^{-}$

Thus, no. of electrons transferred n = 4

$\Delta G = - nFE = - 4 \times 96500 \times E$

Or $966 \times 10^{3} = - 4 \times 96500 \times E$

$\Rightarrow E = - \frac{966 \times 10^{3}}{4 \times 96500} = - 2.5V$

Question: The Gibb’s energy for the decomposition of \(Al_{2}O_{3}\) at \(500ºC\) is as follows: \[2/3Al_{2}O...