Please provide the soln with full explanation and also which metal can be taken as anode or cathode and wh

Asked by ayushi | 8th Jul, 2016, 10:01: AM

Expert Answer:

  • In practice, the reaction will proceed if the E° value of the reaction is greater than + 0.40V.
  • An equation with a more positive E° value will reverse one which is less positive.
 
Hence if an Sn(s) / Sn2+ (aq) cell and a Cu(s) / Cu2+ (aq) cell are connected:
  • The appropriate equations are:  Cu2+ (aq) + 2e¯ → Cu(s) ; E° = +0.36V     Sn2+ (aq) + 2e¯ →  Sn(s) ; E° = -0.136 V
  • The half reaction with the more positive E° value is more likely to work
  • It gets the electrons it needs by reversing the half reaction with the lower E° value
  • So,  Cu2+ (aq) ——> Cu(s) and Sn(s) ——> Sn2+ (aq)
  • The overall reaction is Cu2+ (aq) + Sn(s) ——> Sn2+ (aq) + Cu(s)
  • The cell voltage will be the difference in E° values ... (+0.34) - (-0.14) = + 0.48V
  • Hence, Sn2+ (aq)  +  Cu (s)  →  Sn (s)  +  Cu2+(aq) is not feasible.

Answered by Prachi Sawant | 8th Jul, 2016, 04:17: PM