Question

Standard electrode potential values, E° of $Al^{3+}$ / Al is – 1.66 V and that of $Tl^{3+}$/Tl is 1.26 V. Predict about the formation of $M^{3+}$ ion in solution and compare the electropositive character of the two metals.

Answer 1

"The given two half-cell reactions are as follows

For$\quad A{ l }^{ 3+ }/Al\quad { E }^{ - }\quad =\quad -1.66\quad V$

For$\quad T{ I }^{ 3+ }/Tl\quad { E }^{ - }\quad =\quad +1.26\quad V$

From the above "two half-cell" reactions, standard electrode potential values for "two half-cell" reactions indicate that aluminium has high tendency to form trivalent form, i.e., ${ Al }^{ 3+ }(aq)$.

But it is not applicable to ${ Tl }^{ 3+ }$ because it is unstable ion and it is strong oxidizing agent.

The stable form of this ion is ${ Tl }^{ + }$

Therefore, aluminium easily form trivalent ion and more electropositive than Thallium."