PLQ -Redox Titration

What substance is used to standardize the KMnO₄ solution?

• H₂O₂
  

• Sodium oxalate

• 6N H₂SO₄

• 0.100 N KMnO₄

• Agua oxenada solution

What color change indicates the endpoint in KMnO₄ titration?

• Brown to pink

• Disappearance of pink

• Colorless to green

• Permanent faint pink

• Yellow to colorless

Answer explanation

The endpoint is marked by the first faint pink color that persists.

Which of the following is not required in the standardization procedure?

• H₂SO₄

• KMnO₄ solution

• H₂O₂

• Na₂C₂O₄

• Distilled water

Answer explanation

H₂O₂ is used later for unknown analysis, not in standardization.

Which of the following should not be done during KMnO₄ preparation?

• Stir the solution

• Boil the solution

• Use pre-boiled distilled water

• Store in a dark place

• Dissolve 3.2 g KMnO₄ in hot water

Answer explanation

Boiling accelerates KMnO₄ decomposition.

What is the ideal temperature of the oxalate solution before titration?

• Room temperature

• ~60°C

• ~85°C

• Boiling point

• 0°C

Answer explanation

Heating to ~85°C ensures a faster and complete reaction.

What equipment is used to deliver KMnO₄ solution during titration?

• Acid burette

• Base burette

• Erlenmeyer flask

• Pipette

• Glass Cylinder

Answer explanation

An acid burette is suitable for strongly colored and oxidizing titrants like KMnO₄.

What is used to clean the burette before filling with KMnO₄?

• Ethanol

• Liquid Detergent

• KMnO₄ solution

• Distilled Water

• NaOH

Answer explanation

Burette should be rinsed with KMnO₄ solution to avoid dilution errors.

What meniscus should be read when using colored solutions like KMnO₄?

• Side

• Any visible point

• Lower

• Center

• Upper

Answer explanation

The upper meniscus is observed due to KMnO₄’s deep purple color.

What is the expected product when KMnO₄ reacts with H₂O₂

• MnO₂

• H₂

• Mn⁶⁺

• CO₂

• Mn²⁺

What is the gas evolved during standardization reaction?

• H₂

• O₂

• CO₂

• NO₂

• CH₄