What is the half-reaction method?

The half-reaction method splits a redox reaction into two separate equations — one for oxidation and one for reduction — balances each independently, then combines them so electrons cancel.

How does the solution type affect balancing?

In acidic solution, H⁺ and H₂O are added to balance hydrogen and oxygen. In basic solution, OH⁻ is used instead: after balancing in acid, add OH⁻ to both sides to convert H⁺ into H₂O.

What are oxidation states?

Oxidation states (or oxidation numbers) are hypothetical charges assigned to atoms in a molecule based on electronegativity rules. An increase in oxidation state = oxidation (loss of electrons); a decrease = reduction (gain).

Can I balance any arbitrary redox reaction here?

This tool works with the built-in preset reactions, which cover the most common examples taught in general chemistry. Each preset shows the full step-by-step logic so you can apply the same method to other reactions.

What does "LEO the lion says GER" mean?

It is a mnemonic: Loss of Electrons = Oxidation; Gain of Electrons = Reduction. The species that loses electrons is the reducing agent; the one that gains electrons is the oxidizing agent.

Redox Half-Reaction Balancer

Name: Redox Half-Reaction Balancer
Availability: InStock
Author: Nham Vu

Enter a redox reaction and get step-by-step half-reaction balancing with oxidation states shown.

Select Reaction

Solution Medium

Acidic (H⁺) Basic (OH⁻)

Oxidation State Rules

• Free element: 0

• Monatomic ion: = charge

• O in compounds: −2 (except peroxides: −1)

• H in compounds: +1 (metal hydrides: −1)

• Sum of states in neutral = 0; in ion = charge

LEO says GER: Loss of e⁻ = Oxidation; Gain of e⁻ = Reduction

Select a preset and click Balance Reaction.

Summary

Enter a redox reaction and get step-by-step half-reaction balancing with oxidation states shown.

How it works

Select a preset redox reaction or enter species manually.
Choose whether the reaction occurs in acidic or basic solution.
The tool splits the reaction into oxidation and reduction half-reactions.
Each half-reaction is balanced for atoms and charge, adding H⁺/OH⁻ and H₂O as needed.
Electrons are equalized between the two half-reactions.
The balanced overall ionic equation is displayed.

Use cases

Check redox equation balancing for chemistry homework.
Learn the half-reaction method step by step.
Verify oxidation state assignments for each species.
Practice balancing reactions in acidic vs. basic conditions.
Understand electron transfer in electrochemical cells.
Prepare for AP Chemistry or college general chemistry exams.

Frequently Asked Questions

Last updated: 2026-06-18 · Reviewed by Nham Vu