In: Chemistry
1. Balance the following oxidation-reduction reactions using the half-reaction method and tell the number of electrons transferred in the balanced oxidation-reduction reaction
a) S2-(aq) + NO3-(aq) ---> S8(s) + NO2(g) acidic solution
b) MnO4-(aq) + I-(aq) ---> MnO2(s) + IO3-(aq) basic solution
c) Sb(s) + H2SO4(aq) ---> Sb2(SO4)3(s) + SO2(g) acidic solution
d) H2O2(aq) + MnO4-(aq) ---> MnO2(s) + O2(g) basic solution
a) S2-(aq) + NO3-(aq) ---> S8(s) + NO2(g)
oxidation half reaction : S2-(aq) ----------> S8(s)
8S2-(aq) ----------> S8(s) + 16 e-
reduction half reaction : NO3-(aq) ----------> NO2(g)
NO3-(aq) + 2H+(aq) + e- ----------> NO2(g) + H2O(l)
16 x ( NO3-(aq) + 2H+(aq) + e- ----------> NO2(g) + H2O(l) )
16NO3-(aq) + 32H+(aq) + 16e- ----------> 16NO2(g) + 16H2O(l)
8S2-(aq) ----------> S8(s) + 16 e-
16NO3-(aq) + 32H+(aq) + 16e- ----------> 16NO2(g) + 16H2O(l)
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8S2-(aq) + 16NO3-(aq) + 32H+(aq) ------------> S8(s) + 16NO2(g) + 16H2O(l)
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b)
oxidation half reaction : I-(aq) ---------------> IO3-(aq)
reduction half reaction : MnO4-(aq) --------------> MnO2(s)
balanced equation : 2 MnO4-(aq) + I-(aq) + H2O(l) ------------> 2 MnO2(s) + IO3-(aq) + 2OH-(aq)
total no.of electrons transferred = 6
c)
oxidation half reaction : Sb(s) ---------------> Sb3+(aq)
reduction half reaction : SO42- (aq) ------------> SO2(g)
balanced : 2Sb + 12H+ + 3SO4-2 --> 2Sb+3 + 3SO2 + 6H2O
total no. of electrons transferred = 6