Balancing redox reactions using the ion-electron (half-reaction) method

Vocabulary flashcards covering key terms and steps from the notes on balancing redox reactions using the ion-electron (half-reaction) method.

Ion-electron method

A method to balance redox reactions by balancing oxidation and reduction half-reactions separately and then combining them by canceling electrons.

Half-reaction method

Another name for the ion-electron method; balance oxidation and reduction half-reactions individually.

Oxidation half-reaction

The half-reaction in which a species loses electrons.

Reduction half-reaction

The half-reaction in which a species gains electrons.

Step 1: Separate half-reactions

Identify and separate the oxidation and reduction half-reactions in the overall redox equation.

Step 2: Balance atoms except O and H

In each half-reaction, balance all elements other than oxygen and hydrogen.

Step 3: Balance O with H2O

Balance oxygen atoms by adding water molecules to the appropriate side.

Step 4: Balance H with H+

Balance hydrogen by adding hydrogen ions (H+) in acidic solution.

Step 5: Balance charge with electrons

Add electrons to balance the net charge of each half-reaction.

Step 6: Combine and cancel electrons

Add the half-reactions together and cancel electrons to obtain the overall balanced equation.

MnO4- (permanganate ion)

A common oxidizing agent; in acidic solution it is reduced to Mn2+.

S2+ and S4+

Sulfur-containing species used in the example; S2+ is oxidized to S4+ by MnO4-.

Acidic medium

Redox balancing context where H+ is available; balancing uses H+, H2O, and electrons.

Basic medium

Redox balancing context where OH- is used to neutralize H+ to form water; balancing occurs in basic conditions.

Converting acidic to basic conditions

Process of transforming an acidic redox balance into basic conditions by adding OH- and forming water.

Basic balanced reaction (example)

The balanced redox equation under basic conditions, obtained after converting from acidic conditions.