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Redox Reactions

Redox ReactionsNEET Chemistry · Class 11 · NCERT Chapter 7

2 interactive concept widgets for Redox Reactions. Drag any slider, change any number, and watch the formula and the answer update live. Built so you understand how each NEET problem actually works, not just the final number.

Oxidation number assignment

See oxidation states assigned to every atom in 15 compounds and ions. Each step traces the rules applied (free element, monatomic ion, O = −2, H = +1, sum rule).

Redox reactions

Oxidation number calculator

Select a compound to find the oxidation state of every element with step-by-step reasoning. Covers KMnO₄, K₂Cr₂O₇, H₂O₂, and 12 more.

Select a compound to see the oxidation state of each element with step-by-step reasoning using the standard rules.

Key rules (in order of priority)

1. Free elements: ox. state = 0 (Fe, O₂, H₂...)

2. Monoatomic ions: ox. state = charge (Na⁺ = +1)

3. O = −2 (exception: O₂ = 0; H₂O₂ = −1; OF₂ = +2)

4. H = +1 bonded to non-metals; H = −1 in metal hydrides

5. F = −1 always (most electronegative)

6. Halogens Cl, Br, I = −1 unless bonded to O or more electroneg. element

7. Sum of all ox. states = 0 (neutral) or = ionic charge

KMnO₄
K₂Cr₂O₇
Na₂SO₄
HNO₃
H₂SO₄
Fe₃O₄
H₂O₂
CrO₄²⁻
MnO₄⁻
Cr₂O₃
SO₂
ClO₃⁻
Na₂O₂
NH₄⁺
PCl₅

KMnO₄

+1

K1)

+7

Mn1)

-2

O4)

1

O is −2 (4 × −2 = −8)

2

K is +1 (Group 1)

3

Sum = 0: +1 + Mn + (−8) = 0

4

Mn = +7

Try this

  • In H₂O₂ and Na₂O₂, oxygen is −1 (not the usual −2). This peroxide exception appears often in NEET.
  • Fe₃O₄ contains both Fe²⁺ and Fe³⁺. Average ox. state = +8/3 (non-integer, but the compound is real).
  • KMnO₄ and K₂Cr₂O₇ are strong oxidizing agents. Their Mn (+7) and Cr (+6) get reduced in reactions.

Redox balancing by half-reaction method

Four preset redox reactions balanced step by step using the ion-electron method. Identify oxidation/reduction half-reactions, balance atoms and charge, then combine.

Redox reactions

Redox reaction balancer

Walk through the ion-electron (half-reaction) method step by step for 4 NEET-relevant redox reactions including KMnO₄, K₂Cr₂O₇, and disproportionation.

Walk through the half-reaction method for balancing redox equations. Reveal each step in sequence.

MnO₄⁻ + Fe²⁺ (acidic)
Cr₂O₇²⁻ + I⁻ (acidic)
MnO₄⁻ + C₂O₄²⁻ (acidic)
Cl₂ + NaOH (basic — disproportionation)

Unbalanced

MnO₄⁻ + Fe²⁺ → Mn²⁺ + Fe³⁺

Medium: acidic

Try this

  • In acidic medium: balance O by adding H₂O; balance H by adding H⁺.
  • In basic medium: balance O by adding OH⁻; balance H by adding H₂O.
  • Electrons transferred in oxidation half-reaction must equal electrons gained in reduction half-reaction.

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