What are the metal ions formed when equimolar amounts of SnCl2 and HgCl2 are mixed?
This question is suggesting that there might be a redox reaction between Sn2+ and Hg2+, otherwise, other than the possible dissociation of the solid salts, nothing will happen. To determine if a reaction occurs, we need to look at the possible oxidation and reduction reactions. Sn2+ can be either oxidized to Sn4+ or reduced to Sn metal. Hg^2+ can only be reduced to Hg2^2+ or Hg metal. Since Hg^2+ can only be reduced, if a reaction occurs, Sn2+ can only be oxidized. So our only possible reaction could be: Sn2+ –> Sn4+ + 2e- 2Hg^2+ + 4e- –> Hg2^2+ ————————————–… 2Sn2+ + Hg2+ –> 2Sn4+ + Hg2^2+ To confirm this we need to look at the sum of the reduction potentials for these two reactions: Sn2+ –> Sn4+ + 2e- ………….. -0.13 V 2Hg^2+ + 4e- –> Hg2^2+ ……. +0.92 V ————————————–… 2Sn2+ + Hg2+ –> 2Sn4+ + Hg2^2+ ….. +0.79 V Since the cell potential is positive, the reaction is spontaneous, and Sn^4+ and Hg2^2+ are formed. Therefore
