Question

Predict whether `Tl^(oplus)` will disproportionate in aqueous solution :
`Tl^(3+) overset (1.25 V) rarr Tl^(oplus) overset (-0.34 V) rarr Tl`.

Answer 1

Disproportionation of `Tl^(oplus)` can be represent as :
`Tl^(oplus) rarr Tl^(2 oplus) + Tl E^(Ө) = ?`….(i)
Given, `2e^(Ө) + Tl^(3+) rarr Tl^(oplus) E^(Ө) = + 1.25 V` ….(ii)
`e^(Ө) + Tl^(oplus) rarr TlE^(Ө) = - 0.34 V` …..(iii)
Eq. (iii) xx (ii) rArr `2 Tl^(oplus) + 2e^(Ө) rarr 2 Tl E^(Ө) = 0.34 V` ...(iv)
Reverse Eq. (ii rArr `Tl^(oplus) rarr Tl^(3+) + 2e^(Ө) E^(Ө) = 1.25 V` ...(v)
Add Eqs, `(iv) + ulbar((v) rArr 3Tl^(oplus) rarr 2 Tl + Tl^(3_+)) + E^(Ө) = - 1.59 V`
Because `E^(Ө)` value is highlye negative, `Tl^(oplus)` will have no tendency for disproportionation.