🎓 Chemistry • Electrochemistry
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Oxidation Number Calculator
Evaluates oxidation numbers for transition metals and central atoms in compounds like KMnO₄, K₂Cr₂O₇, and H₂SO₄.
Select Chemical Compound or Ion
Evaluates target atom oxidation states using IUPAC electronegativity hierarchy.
Popular Examination Presets:
⬅ Reduction (Gain e⁻ / More Negative)Oxidation State Scale (-4 to +8)Oxidation (Loss e⁻ / More Positive) ➔
Mn:+7
Assigned Oxidation Number
+7
For Mn in Potassium Permanganate (KMnO4)
Algebraic Charge Balance Derivation:
1(+1) + 1(Mn) + 4(-2) = 0 ⟹ Mn - 7 = 0 ⟹ Mn = +7
💡 Key Note: Highest possible oxidation state for manganese (d⁰ configuration).
IUPAC Priority Assignment Rules:
- Free Elements: Pure elemental state (e.g. O₂, Fe, S₈) is always 0.
- Monatomic Ions: Oxidation number equals ionic charge (e.g. Na⁺ is +1, Cl⁻ is -1).
- Fluorine: Always -1 in all compounds due to maximum electronegativity.
- Group 1 & 2 Metals: Group 1 is always +1; Group 2 is always +2.
- Hydrogen: +1 with nonmetals (H₂O, HCl); -1 in metal hydrides (NaH, CaH₂).
- Oxygen: -2 in normal oxides; -1 in peroxides (H₂O₂); +2 in OF₂.
- Sum of States: Equals 0 for neutral molecules, or net ionic charge for polyatomic ions.
What is an Oxidation Number?
An oxidation number is the hypothetical charge that an atom would have if all bonds to atoms of different elements were 100% ionic.
Formula & Step-by-Step Calculation
Σ (Oxidation Numbers) = Total Net Charge of Molecule or Ion
Neutral compounds sum to 0; polyatomic ions sum to the overall ionic charge.
Worked Step-by-Step Examples
Example 1
Find oxidation state of Mn in KMnO4
Solution: Mn = +7
• K(+1) + Mn + 4(-2) = 0 ⟹ Mn - 7 = 0 ⟹ Mn = +7
Common Real-World & Academic Use Cases
- ✓ Balancing redox chemical equations
- ✓ Electrochemical battery cell half-reactions
- ✓ Corrosion and metal plating analysis
How to Use the Oxidation Number Calculator
1
Select Compound
Choose from common coordination compounds and ions.
2
Read Oxidation State
Review the step-by-step charge balance algebra.
Frequently Asked Questions
Q: What is the oxidation number of Oxygen in peroxides?
In peroxides like H2O2, oxygen has an oxidation state of -1 rather than the standard -2.