Step 1: Identify oxidation state changes Fe: +0 → +3 (oxidation, loses 3 electrons per atom) O: +0 → -2 (reduction, gains 2 electrons per atom)
Step 2: Calculate electron transfer per compound Fe contains 1 Fe atom, each losing 3 electrons = 3 electrons lost per Fe O2 contains 2 O atoms, each gaining 2 electrons = 4 electrons gained per O2
Step 3: Write half-reactions Oxidation: Fe → Fe{3+} + 3e⁻ Reduction: O + 2e⁻ → O{2-}
Step 4: Balance electrons to determine coefficients Electrons lost per Fe: 3 Electrons gained per O2: 4 The least common multiple of 3 and 4 = 12 Coefficient for Fe: 12 ÷ 3 = 4 Coefficient for O2: 12 ÷ 4 = 3 Total electrons transferred: 12
Step 5: Complete mass balance Other coefficients are determined by: • Atom conservation (mass balance) • Charge neutrality • Stoichiometric relationships
Step 7: Verify balance ✓ Atoms are balanced ✓ Electrons transferred are equal ✓ Charge is conserved
Instructions for redox reaction analysis:
Enter an equation of a chemical reaction and click 'Analyze'. The answer will appear below
Always use the upper case for the first character in the element name and the lower case for the second character. Examples: Fe, Au, Co, Br, C, O, N, F. Compare: Co - cobalt and CO - carbon monoxide
To enter an electron into a chemical equation use {-} or e
To enter an ion, specify charge after the compound in curly brackets: {+3} or {3+} or {3}. Example: Fe{3+} + I{-} = Fe{2+} + I2
What are redox reactions?
Redox (reduction-oxidation) reactions are chemical reactions in which atoms have their oxidation states changed. These reactions involve the transfer of electrons between chemical species.
Key concepts:
Oxidation: Loss of electrons, increase in oxidation state
Reduction: Gain of electrons, decrease in oxidation state
Oxidizing agent: Species that causes oxidation (gets reduced itself)
Reducing agent: Species that causes reduction (gets oxidized itself)
Example: CuCl2 + Al → Cu + AlCl3
Let's analyze this step by step:
Assign oxidation states: CuCl₂: Cu = +2, Cl = -1 Al: Al = 0 Cu: Cu = 0 AlCl₃: Al = +3, Cl = -1
