✔ 最佳答案
Bi2O3 + ClO- .----------------------------> BiO3 - + Cl-
reduction half reaction------
ClO-1 ----------------------> Cl-1
add H2O to balance oxygen
ClO-1 ----------------------> Cl-1 + H2O
add 2H+ to balance hydrogen
ClO-1 + 2H+ ----------------> Cl-1 + H2O
to balance charge on both sides add e- to the side rich in +ve charge
ClO-1 + 2H+ + 2e- -------------------> Cl-1 + H2O
add 2OH- on both sides
ClO-1 +2H+ +2OH- +2e- ----------------> Cl-1 + H2O +2OH-
or ClO-1 +2H2O + 2e- ---------> Cl-1 + H2O + 2OH-
or ClO-1 + H2O +2e- -----------------> Cl-1 + 2OH- --------------(I)
oxidation half reaction ---------
Bi2O3 -----------------> BiO3-1
balancing Bi on both sides
Bi2O3 ---------------> 2 BiO3-1
add H2O to balance Oxygen
Bi2O3 + 3H2O -------------> 2BiO3-1
add H+ to balance hydrogen
Bi2O3+3 H2O ----------------> 2BiO3-1 + 6H+
add e- to balance charge
Bi2O3 + 3H2O -------------> 2BiO3-1 + 6H+ + 4e-
add 6OH- on both sides
Bi2O3 + 3H2O + 6OH- -------------> 2BiO3-1 + 6H+ + 6OH- + 4e-
or Bi2O3 + 3H2O + 6OH- ---------> 2BiO3-1 + 6H2O + 4e-
or Bi2O3 + 6OH- ----------------> 2BiO3-1 + 3H2O + 4e- -----------------(II)
multiply reaction (I) by 2 and add (I) & (II)
Bi2O3 + 2ClO-1 + 2OH- -----------> 2BiO3-1 + 2Cl-1 + H2O
this is the balanced equation
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2. reduction half reaction----
MnO4-1 -----------------> MnO2
MnO4-1 -------------> MnO2 +2 H2O
MnO4-1 + 4H+ -------------> MnO2 + H2O
MnO4-1 + 4H+ + 4OH- --------> MnO2 + 2H2O + 4OH-
or MnO4-1 + 4H2O ------> MnO2 + 2H2O + 4OH-
or MnO4-1 + 2H2O -+ 3e----------> MnO2 + 4OH- --------------------(I)
oxidation half reaction ---
S-2 ---------------> S
S-2 ----------------> S + 2e- -------------------(II)
multiply (I) by 2 & (II) by 3 and add
2MnO4-1 + 3S-2 4H2O -------> 2MnO2 + 3S +8OH-
this is the balanced reaction
參考: i am M.Sc. chem. (1973) ex- principal ex- examiner