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:

1. Assign oxidation states:
   CuCl₂: Cu = +2, Cl = -1
   Al: Al = 0
   Cu: Cu = 0
   AlCl₃: Al = +3, Cl = -1
2. Identify changes:
   Cu: +2 → 0 (reduced, gains 2 electrons)
   Al: 0 → +3 (oxidized, loses 3 electrons)
3. Balance electrons:
   Cu²⁺ + 2e⁻ → Cu (reduction)
   Al → Al³⁺ + 3e⁻ (oxidation)
   LCM of 2 and 3 = 6 electrons
   3 Cu²⁺ + 6e⁻ → 3 Cu
   2 Al → 2 Al³⁺ + 6e⁻
4. Identify agents:
   CuCl₂ is the oxidizing agent (causes Al to be oxidized)
   Al is the reducing agent (causes Cu to be reduced)
5. Balance equation:
   3 CuCl₂ + 2 Al → 3 Cu + 2 AlCl₃

Example equations for redox analysis:

• CuCl2 + Al = Cu + AlCl3
• CuCl2 + Fe = Cu + FeCl2
• Zn + CuSO4 = ZnSO4 + Cu
• H2 + Cl2 = HCl
• Fe + O2 = Fe2O3
• KMnO4 + HCl = MnCl2 + KCl + H2O + Cl2
• S{-2} + I2 = I{-} + S
• Al + CuO = Al2O3 + Cu
• Mg + AgNO3 = Mg(NO3)2 + Ag

How to balance redox equations

Redox equations can be balanced using the electron transfer method:

1. Identify the elements being oxidized and reduced
2. Write separate half-reactions for oxidation and reduction
3. Balance atoms in each half-reaction
4. Balance charge by adding electrons
5. Multiply half-reactions to equalize electrons
6. Add half-reactions and simplify

Video lesson on redox reactions

Related:

• Chemical equation balancer
• Oxidation State Calculator
• Limiting Reagent Calculator