Potassium permanganate, KMnO4, is a powerful oxidizing agent. The products of a

Question

Potassium permanganate, KMnO4, is a powerful oxidizing agent. The products of a given redox reaction with the permanganate ion depend on the reaction conditions used. In basic solution, the following equation represents the reaction of this ion with a solution containing sodium cyanide:

MnO4?(aq)+CN?(aq)?MnO2(s)+CNO?(aq)

Since this reaction takes place in basic solution, H2O(l) and OH?(aq) will be shown in the reaction. Places for these species are indicated by the blanks in the following restatement of the equation:

MnO4?(aq)+CN?(aq)+     ????MnO2(s)+CNO?(aq)+     ???

What are the coefficients of the reactants and products in the balanced equation above? Remember to include H2O(l) and OH?(aq) in the blanks where appropriate. Your answer should have six terms.

Explanation / Answer

It is usually easier to balance these reactions in acid first. Then you can convert them to base.

Split into half reactions and then balance these in acidic solution. Then add them together making sure you cancel the electrons. Then convert to basic solution. You balance O by adding H2O, H by adding H^+, and electrons by adding them to the more positive side of the equation until both sides have an equal sum of the charges.

MnO4^- ? MnO2
MnO4^- ? MnO2 + 2H2O (balance O)
MnO4^- + 4H^+ ? MnO2 + 2H2O (balance H)
MnO4^- + 4H^+ + 3e^- ? MnO2 + 2H2O (balance electrons; both sides have a total charge of 0 now)

F^- ? F2
2F^- ? F2
2F^- ? F2 + 2e^-

To balance the electrons between them, you need the F equation times 3 and the Mn equation times 2.

2MnO4^- + 8H^+ + 6e^- ? 2MnO2 + 4H2O
6F^- ? 3F2 + 6e^-

Related Questions

Navigate

• Browse (All)
• Browse P
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.