什麼是 Oxidation Number Calculator？
Calculate oxidation numbers (oxidation states) for elements in a chemical formula using standard general-chemistry rules. Enter a compound like H₂SO₄ or an ion like SO₄ with charge −2, and get each element's oxidation state with the reasoning applied. Supports manual overrides for tricky cases. Runs instantly in your browser with no signup.
如何使用 Oxidation Number Calculator
- Enter the chemical formula (e.g. H2SO4, KMnO4, Cr2O7).
- Set the overall charge — 0 for neutral molecules, −2 for sulfate, −1 for permanganate, etc.
- Review oxidation numbers in the results table and the charge-balance equation.
- Add a manual override if multiple elements would otherwise stay unknown.
- Copy the summary for notes or redox homework.
常見用途
- Finding sulfur's +6 oxidation state in sulfuric acid
- Balancing redox equations with MnO₄⁻ or Cr₂O₇²⁻
- Checking oxidation states before assigning electrons in half-reactions
常見問題
- What is an oxidation number?
- It is the hypothetical charge an atom would have if bonds were completely ionic. In H₂O, oxygen is −2 and hydrogen is +1. They sum to zero in a neutral molecule.
- How do I enter an ion like SO₄²⁻?
- Use the formula without the charge in the formula field (SO4) and enter −2 in the overall charge field.
- What rules does this calculator use?
- Standard rules: free elements are 0; group 1 is +1, group 2 is +2; Al is +3; F is −1; O is usually −2 (peroxides −1); H is usually +1 (hydrides −1); Cl/Br/I are −1 in binary halides without oxygen.
- Why does S₂O₃²⁻ show one sulfur oxidation state?
- Thiosulfate has sulfur atoms in different environments. This tool reports one oxidation state per element symbol (an average) unless you add manual overrides.
- Can it handle fractional oxidation states?
- Yes. Magnetite (Fe₃O₄) gives an average iron oxidation state of +8/3 when oxygen is assigned −2.
