Question

Balance the Redox reaction with Steps. Which elements are Oxidized and Reduced?
MnO4- + S2- + H+ --------> Mn2+ S + H20

Answer 1

Answer:

Write the skeletal equation for the reaction and identify what is oxidized and what is reduced.

MnO4

-

+ S2-

 MnS + S

S

2-

is oxidized, going from -2 to 0

Mn is reduced, going from +7 to +2

2) Write the initial half reactions for the oxidation and reduction reactions.

Oxidation: S2-

 S

Reduction: MnO4

-

 MnS

3) Balance elements other than H and O

Oxidation: S2-

 S

Reduction: MnO4

-

+ S2-

 MnS

4) Balance O by adding water.

Oxidation: S2-

 S

Reduction: MnO4

-

+ S2-

 MnS + 4 H2O

5) Balance H by adding H+

. Then, add that same number of OHto both sides of the half reaction.

Simply by combining H+

and OHto form H2O.

Oxidation: S2-

 S (no hydrogen in reaction so leave as is for this step)

Reduction: 8H+

MnO4

-

+ S2-

 MnS + 4H2O (adding H+

)

Reduction: 8OH-

+ 8H+

MnO4

-

+ S2-

 8OH-

+ MnS + 2H2O (adding OH-

)

Reduction: 8 H2O + MnO4

-

+ S2-

 8 OH-

+ MnS + 4H2O (forming water)

6) Balance charge by adding electrons (e-

)

Oxidation: S2-

 S + 2eReduction: 5e-

+ 8 H2O + MnO4

-

+ S2-

 8 OH-

+ MnS + 4H2O

At this point, the individual half reactions are balanced.

Explanation: