Question

balance the equation AsO3 - 3 + MnO4- — AsO4 - 3 + Mn2O3 is basic medium by half reaction method ​

Answer 1

the balanced chemical equation would be

Answer 2

1. Separate into half reactions

MnO4- ---> MnO2

(AsO3)3- ---> (AsO4)3-

2. Add water to balance out the oxygens

MnO4- --> MnO2 + 2H2O

(AsO3)3- + H2O --> (AsO4)3-

3. Balance it like it's in an acidic solution (Add H+ to balance hydrogens)

MnO4- + 4H+ ---> MnO2 + 2H2O

(AsO3)3- + H2O --> (AsO4)3- + 2H+

4. Add electrons to balance out charges

3e- + MnO4- + 4H+ ---> MnO2 + 2H2O

(AsO3)3- + H2O --> 2e- + (AsO4)3- + 2H+

5. Common denominator is 6, so .. multiply first equation by 2 and second equation by 3. Add equations up.

6e- + 2MnO4- + 8H+ ---> 2MnO2 + 4H2O

3(AsO3)3- + 3H2O --> 6e- + 3(AsO4)3- + 6H+

-------------------------------------------------------

2MnO4- + 2H+ +3(AsO3)3- ---> 2MnO2 + H2O + 3(AsO4)3-

5. Add OH- to both sides to get rid of H+ (since they want answer to be in basic solution)

2MnO4- + 2H+ +2OH- +3(AsO3)3- ---> 2MnO2 + H2O + 3(AsO4)3- +2OH-

2MnO4- + 2H2O +3(AsO3)3- ---> 2MnO2 + H2O + 3(AsO4)3- +2OH-

2MnO4- + H2O +3(AsO3)3- ---> 2MnO2 + 3(AsO4)3- +2OH-

Hope that's right.