Given the standard electrode potentials,
K+K=−2.93 V,
Ag+Ag=0.80 V
Hg2+Hg=0.79V,
Mg2+Mg=−2.37 V
Cr3+Cr=−0.74 V
Arrange these metals in their increasing order of reducing power.
Metal which has lower reduction potential (more negative E value) has greater reducing capacity because it itself gets oxidised more easily.
MetalsReduction,Potentials(volts)∣∣∣Ag<Hg<Cr<Mg<K−−−−−−−−−−−−−−−−−−−→Reducing power increases0.80>0.79>−0.74>−2.37>−2.93−−−−−−−−−−−−−−−−−−−→Reducing power increases
The lower the reduction potential, the higher is the reducing power. The given standard
electrode potentials increase in the order of
K+K < Mg2+Mg < Cr3+Cr < Hg2+Hg < Ag+Ag
Hence, the reducing power of the given metals increases in the following order:
Ag < Hg < Cr < Mg < K