Oxidation Number Calculator - Oxidation State Calculator & Redox Calculator
Free oxidation number calculator & oxidation state calculator. Calculate oxidation numbers in compounds, find oxidation states, and solve redox reactions with step-by-step solutions. Our chemistry calculator helps you master oxidation-reduction chemistry and electron transfer concepts.
Last updated: December 15, 2024
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Enter a common compound formula
Oxidation Number Result
Oxidation number of S in H2SO4
+6
Calculation Steps:
- Compound: H2SO4
- Element: S
- Apply oxidation number rules
- Oxidation number of S = +6
Explanation:
In H2SO4, S has an oxidation number of +6
Oxidation Number Rules:
- • Free elements: oxidation number = 0
- • Group 1 metals: always +1, Group 2: always +2
- • Oxygen: usually -2 (except peroxides: -1)
- • Hydrogen: usually +1 (except metal hydrides: -1)
- • Fluorine: always -1
- • Sum of oxidation numbers = charge of species
Oxidation Number Calculator Methods & Applications
Method
Rules-Based Analysis
Apply systematic rules to determine oxidation numbers
Analysis
Electron Transfer
Identify oxidation and reduction in chemical reactions
Technique
Sum = Charge
Use algebra to find oxidation numbers in complex compounds
Database
H₂SO₄, KMnO₄, HNO₃
Instant results for commonly studied compounds
Elements
S, N, Mn, Cr, Fe
Determine oxidation states for transition metals and more
Rules applied
6 Key Rules
Systematic approach using established chemistry rules
Quick Example Result
Oxidation number of sulfur in H₂SO₄:
Oxidation State of S
+6
Calculated: 2(+1) + x + 4(-2) = 0
How Our Oxidation Number Calculator Works
Our oxidation number calculator uses systematic chemistry rules and algebraic methods to determine oxidation states of elements in compounds. The calculator applies established oxidation number rules and solves equations to find oxidation states in even the most complex compounds.
Oxidation Number Rules & Formula
Rule 1: Free elements = 0Rule 2: Monoatomic ions = ion chargeRule 3: Group 1 = +1, Group 2 = +2Rule 4: Oxygen = -2 (usually)Rule 5: Hydrogen = +1 (usually)Rule 6: Sum of oxidation numbers = total chargeThese fundamental rules govern oxidation number assignment. For neutral compounds, the sum equals zero; for ions, it equals the ion charge. The algebraic method uses these rules to solve for unknown oxidation states.
Shows electron transfer and oxidation state changes in redox reactions
Algebraic Method for Finding Oxidation Numbers
The algebraic method is powerful for finding unknown oxidation numbers. Set up an equation where the sum of all oxidation numbers equals the total charge (0 for neutral molecules, the ion charge for polyatomic ions). Solve for the unknown variable representing the oxidation number you need.
- Identify known oxidation numbers using the rules
- Let x = the unknown oxidation number
- Write equation: sum of all oxidation numbers = total charge
- Multiply each oxidation number by its subscript
- Solve the equation algebraically for x
- Verify the result makes chemical sense
Sources & References
- Chemistry: The Central Science - Brown, LeMay, Bursten (14th Edition)Standard reference for oxidation-reduction chemistry and oxidation states
- General Chemistry: Principles and Modern Applications - Petrucci, Harwood, HerringComprehensive coverage of oxidation number rules and redox reactions
- IUPAC - International Union of Pure and Applied ChemistryOfficial nomenclature and oxidation state conventions
Need help with other chemistry calculations? Check out our balance equation calculator and mole calculator.
Get Custom Calculator for Your Chemistry CourseOxidation Number Calculator Examples
Given Information:
- Compound: H₂SO₄ (sulfuric acid)
- Find: Oxidation number of S
- Known: H = +1, O = -2
- Total charge: 0 (neutral compound)
Calculation Steps:
- Set up equation: 2(H) + 1(S) + 4(O) = 0
- Substitute known values: 2(+1) + x + 4(-2) = 0
- Simplify: 2 + x - 8 = 0
- Solve for x: x = 8 - 2 = +6
Result: The oxidation number of sulfur in H₂SO₄ is +6
Sulfur is in its highest common oxidation state in sulfuric acid
Oxidation Number of Nitrogen in HNO₃
Algebraic method
(+1) + x + 3(-2) = 0 → x = +5
Oxidation Number of Mn in KMnO₄
Potassium permanganate
(+1) + x + 4(-2) = 0 → x = +7
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