Using Potassium Permanganate & Iodine

Potassium permanganate, also known as potassium manganate(VII), is a common chemical used in redox titrations. It is particularly useful in such titrations because it can act as its own indicator. Here are the key points to understand about using potassium permanganate in redox titrations:

Self-Indicator Property:

• Potassium permanganate acts as both the titrant (the solution of known concentration) and the indicator in redox titrations.
• It undergoes a colour change during the titration, which serves as an indicator for the endpoint.

Colour Change:

• In a redox reaction, potassium permanganate undergoes a distinct colour change.
• Initially, it is purple.
• During the titration, as it reacts and gets reduced, it turns clear or pale pink.

Reading the Endpoint:

• Reading the endpoint in MnO4- (permanganate) titrations can be challenging due to the dark colour.
• To mitigate this, it's advisable to read the top of the meniscus rather than the bottom for a more accurate determination of the endpoint.

Using Iodine as an Indicator

Iodine can also be used as an indicator in certain chemical reactions. Here's how it works:

Blue/Black Colour Formation:

• Iodine (I2) reacts with starch to produce a distinct blue/black colour.
• This colour change serves as an indicator in reactions involving iodine.

Redox Potential:

• In redox reactions, iodine undergoes a change in oxidation state from I2 to 2I-.
• I2 (s) + 2e- → 2I- (aq)

---

Using Potassium Permanganate & Iodine

Conclusion:

• Potassium permanganate is a valuable chemical in redox titrations because it acts as both a titrant and an indicator.
• Its characteristic colour change, from purple to clear or pale pink, signals the endpoint of the titration.
• Iodine, when combined with starch, produces a distinctive blue/black colour, making it useful as an indicator in certain chemical reactions, especially those involving redox reactions.