KMnO₄ in burette vs acidified oxalic acid in flask — visual titration and interactive normality calculations.
SaitechAI · KMnO₄–C₂H₂O₄·2H₂O Standardisation
1. Standard Oxalic Acid (Primary Standard)
Oxalic acid dihydrate (H₂C₂O₄·2H₂O); equivalent weight in this redox titration = 63 g/eq.
Prepare Standard Oxalic Acid
N = (W × 1000) / (Eq.wt × V)
g
mL
Normality of oxalic acid (Nox): 0.10 N
2. Titration Data (KMnO₄ vs Oxalic Acid)
KMnO₄ is in the burette (titrant), standard oxalic acid is in the conical flask (analyte).
Experimental Readings
N₁V₁ = N₂V₂
mL
mL
Normality of KMnO₄ (NKMnO₄): 0.099 N
Relation used: Nox Vox = NKMnO₄ VKMnO₄
Concept Check:
• KMnO₄ is a self-indicator in acidic medium, so no external indicator is used.
• In this titration, oxalic acid is the primary standard; KMnO₄ solution is secondary and is
standardised against it.
• Once NKMnO₄ is known, the same solution can be used to estimate other reducing agents
(Fe²⁺, H₂O₂, etc.).
3. Visual Titration Simulator
Status: Pre-endpoint (colourless)
KMnO₄ (in burette)
Acidified Oxalic Acid
Delivered volume: 0.0 mL
| Endpoint (VKMnO₄ from data):
10.1 mL
• Before endpoint: oxalic acid is in excess and decolourises each drop of purple KMnO₄.
• At endpoint: a very faint, permanent pink colour persists (slight excess of KMnO₄).
• Beyond endpoint: solution becomes more strongly pink → over-titration.
Normality relationship used in calculator: Nox × Vox = NKMnO₄ × VKMnO₄
where volumes are in mL and N is in equivalents per litre (N).
For oxalic acid dihydrate: Nox = (W × 1000) / (63 × Vsolution)