A solution containing 1 mol per litre of each Cu(NO3)2,AgNO3, and Hg2(NO3)2 is being electrolyzed by using inert electrodes. The values of standard electrode potentials in volts (reduction potential) are
Ag|Ag⨁=+0.80,2Hg|Hg2+2=+0.79
Cu|Cu2+=+0.34,Mg|Mg2+=−2.37
with increasing voltage, the sequence of deposition of metals at the cathode will be
(IIT-JEE, 1984)
Ag,Hg,Cu,Mg
Higher the oxidation potential, more easily it is oxidized and faster is the deposition of metal.
Decreasing order of E⊖oxidation is:
E⊖Ag|Ag⨁(0.80)>E⊖2Hg|Hg2+2(0.79)>E⊖Cu|Cu2+(0.34)>E⊖Mg|Mg2+(−2.37)
Hence, the sequence of deposition of metals at the cathode will be Ag, Hg, and Cu.