Introduction
Redox titrations involve a redox reaction between a titrant (a solution of known concentration) and an analyte (unknown concentration) to determine its amount. Unlike acid-base titrations, they involve electron transfer and often use colored oxidizing or reducing agents like KMnO₄, K₂Cr₂O₇, or Na₂S₂O₃.

🔹 1. Common Redox Titrants and Their Reactions

🔹 2. Equipment Used

• Burette (holds titrant)

• Pipette (measures analyte)

• Conical flask

• White tile (for color visibility)

• Indicators (if needed — but not for KMnO₄, which is self-indicating)

🔹 3. General Titration Procedure

1. Rinse all apparatus with correct solutions.

2. Fill burette with titrant (e.g., KMnO₄).

3. Pipette analyte (e.g., Fe²⁺) into flask.

4. Add acid (if required, e.g., H₂SO₄ with KMnO₄).

5. Titrate until end-point (color change observed).

6. Repeat for accurate titres (within ±0.10 mL).

7. Calculate unknown concentration.

🔹 4. Example Calculation

Titration of Fe²⁺ with KMnO₄

Reaction:

Data:

• Volume of KMnO₄ used = 25.00 mL

• Molarity of KMnO₄ = 0.0200 mol/L

• Volume of Fe²⁺ = 20.00 mL

• Find molarity of Fe²⁺

Step 1: Moles of KMnO₄

Step 2: Molar ratio (from equation):

Step 3: Molarity of Fe²⁺

✅ Answer: Molarity of Fe²⁺ = 0.125 M

🔹 5. Common Redox Titration Pairs in NECTA

🧠 NECTA Tips

• KMnO₄ is self-indicating: endpoint = faint permanent pink

• Use starch only near endpoint when titrating iodine

• Use H₂SO₄, not HCl or HNO₃, with KMnO₄

• Balance redox equations with electrons

• Always include units in final answers

✅ Summary

• Redox titrations use redox reactions to find unknown concentrations

• KMnO₄, K₂Cr₂O₇, and Na₂S₂O₃ are common titrants

• Must balance reactions and apply mole ratios

• Endpoint is based on color change (self or with indicator)

• Strong NECTA candidate, both theory and practical