$(30)$ For Equilibrium between $Al$ and $A{l}_2{O}_3$ at $1273C,$

a$)$ Determine the standard enthalpy, entropy and Gibbs free energy of formation of

$A{l}_2{O}_3$ at $298K$ from Ellingham diagram. Compare the results in $1.$a$.$

b$)$ Read the equilibrium oxygen pressure $p{O}_2(g),p{H}_2\frac{g}{p}{H}_{2}O(g)$ ratio, and

pCO$\frac{g}{p}C{O}_2(g)$ ratio from the Ellingham diagram using correct scales!

c$)$ Write chemical reactions for $Al(l)$ used for these three different scales.

d$)$ What must be the gas mixture for all to protect $Al(I)$ from oxidation? Use equilibrium

constants!!