Redox Change Calculator
Enter oxidation states before and after reaction for two species. The calculator identifies oxidation/reduction, electron transfer, and electron-balancing multipliers.
Species A
Species B
What this oxidation and reduction calculator does
This tool helps you analyze redox changes quickly using oxidation numbers. Instead of balancing a full equation first, you can start by checking oxidation-state movement for the key elements and instantly see:
- Which species is oxidized and which is reduced
- How many electrons are lost or gained per atom
- Total electron change after accounting for atom count
- Simple multipliers to match electron loss and gain
- Which reactant is the oxidizing agent and reducing agent
It is especially useful for homework, AP Chemistry review, general chemistry labs, and quick redox checks in electrochemistry topics.
Quick refresher: oxidation vs. reduction
Oxidation
Oxidation means an increase in oxidation number. In electron language, that species loses electrons.
Reduction
Reduction means a decrease in oxidation number. In electron language, that species gains electrons.
The memory trick
Use OIL RIG: Oxidation Is Loss (of electrons), Reduction Is Gain (of electrons).
How to use the calculator
Step 1: Enter Species A and Species B
Add names or formulas for readability (for example, Fe²⁺ and MnO₄⁻). These are optional, but they make the output clearer.
Step 2: Enter oxidation states
Provide the oxidation state before and after reaction for each species. The calculator compares initial and final values to identify redox direction.
Step 3: Enter atom count
If more than one atom of the changing element appears in that species, enter the count. The tool multiplies per-atom electron change by atom count.
Step 4: Interpret the result
Click Calculate Redox and read the classifications, electron transfer values, and suggested multipliers for electron balancing.
Worked example
Suppose iron changes from +2 to +3, and manganese changes from +7 to +2.
- Fe: +2 → +3 (increase by 1) ⇒ oxidized, loses 1 e⁻
- Mn: +7 → +2 (decrease by 5) ⇒ reduced, gains 5 e⁻
- To equalize electrons: multiply Fe change by 5, Mn change by 1
The calculator gives exactly this logic and reports the oxidizing and reducing agents: the reduced species is the oxidizing agent, and the oxidized species is the reducing agent.
Understanding oxidizing and reducing agents
Reducing agent
The reducing agent donates electrons and is itself oxidized. Its oxidation number rises.
Oxidizing agent
The oxidizing agent accepts electrons and is itself reduced. Its oxidation number drops.
Tips for balancing full redox equations
This calculator focuses on oxidation-number changes. For a complete balanced chemical equation, you still need mass and charge balance. A reliable workflow is:
- Split into oxidation and reduction half-reactions
- Balance atoms other than O and H
- Balance oxygen with H₂O
- Balance hydrogen with H⁺ (acidic) or H₂O/OH⁻ (basic)
- Balance charge with electrons
- Scale half-reactions to cancel electrons
- Add and simplify common species
Common mistakes this tool helps prevent
- Mixing up oxidation number increase/decrease
- Ignoring how many atoms actually change state
- Forgetting that electron loss must equal electron gain
- Confusing oxidizing agent with reducing agent
FAQ
Can I use fractional oxidation states?
Yes. While many oxidation numbers are integers, averaged oxidation states in some compounds can be fractional. The calculator accepts decimal values.
Does this balance complete molecular equations automatically?
No. It balances the electron-change relationship between two oxidation-state transformations. Use it as a fast redox-analysis step before full equation balancing.
What if one species shows no change?
The output will mark it as no redox change. In a true redox pair, one species should be oxidized while another is reduced.
Bottom line
If you need a fast, clear way to check oxidation and reduction behavior, this calculator gives immediate insight into electron flow, redox roles, and balancing multipliers. It is simple enough for beginners and efficient enough for advanced review.