p-Block Elements (Group 13 & 14) · Question 16

The standard reduction potential values of some of the p-block ions are given below. Predict the one with the strongest oxidising capacity.

1. E Sn4+/Sn2+ = +0.15 V
2. E Al3+/Al = -1.66 V
3. E Pb4+/Pb2+ = +1.67 V
4. E Tl3+/Tl = +1.26 V

Answer

(3) E Pb4+/Pb2+ = +1.67 V

Solution

Greater (more positive) the standard reduction potential, greater the tendency of the ion to gain electrons, i.e. stronger the oxidising agent.

+1.67 > +1.26 > +0.15 > -1.66

Pb4+ is the strongest oxidising agent. (As per NCERT, the +2 state of Pb is more stable than +4 due to the inert pair effect, so Pb4+ readily changes to Pb2+.)

Answer: (3)