S{-2} + I2 = I{-} + S - Redox Reaction Calculator

Redox Reaction Calculator

This is a redox reaction

Equation with oxidation states:

-2

0
I	₂

→

-1

Redox Agents
Agent Type	Compound	Role
Reducing Agent	S{-2}	Causes reduction, gets oxidized itself
Oxidizing Agent	I₂	Causes oxidation, gets reduced itself

Oxidation State Analysis
Element	In Reagents	In Products	Change
S	-2	0	Oxidized (loses electrons)
I	0	-1	Reduced (gains electrons)

Balanced equation:

S^{-2} + I₂ = 2 I^{-} + S

Step-by-step Solution
Balancing Steps
Step 1: Identify oxidation state changes S: -2 → +0 (oxidation, loses 2 electrons per atom) I: +0 → -1 (reduction, gains 1 electron per atom) Step 2: Calculate electron transfer per compound S{-2} contains 1 S atom, each losing 2 electrons = 2 electrons lost per S{-2} I₂ contains 2 I atoms, each gaining 1 electron = 2 electrons gained per I₂ Step 3: Write half-reactions Oxidation: 2S{2-} → S₂ + 4e⁻ Reduction: I + 1e⁻ → I{-} Step 4: Balance electrons to determine coefficients Electrons lost per S{-2}: 2 Electrons gained per I₂: 2 The least common multiple of 2 and 2 = 2 Coefficient for S{-2}: 2 ÷ 2 = 1 Coefficient for I₂: 2 ÷ 2 = 1 Total electrons transferred: 2 Step 5: Complete mass balance Other coefficients are determined by: • Atom conservation (mass balance) • Charge neutrality • Stoichiometric relationships Step 6: Final balanced coefficients S{-2}: 1 I₂: 1 I{-}: 2 S: 1 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
Identify changes:
Cu: +2 → 0 (reduced, gains 2 electrons)
Al: 0 → +3 (oxidized, loses 3 electrons)
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⁻
Identify agents:
CuCl₂ is the oxidizing agent (causes Al to be oxidized)
Al is the reducing agent (causes Cu to be reduced)
Balance equation:
3 CuCl₂ + 2 Al → 3 Cu + 2 AlCl₃

Example equations for redox analysis:

How to balance redox equations

Redox equations can be balanced using the electron transfer method:

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

Video lesson on redox reactions

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