Which of the following can be used as a primary standard in redox titrations?
2022
Which of the following can be used as a primary standard in redox titrations?
- A.
KMnO₄
- B.
K₂Cr₂O₇
- C.
FeSO₄
- D.
NaOH
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Correct answer: B
Potassium dichromate (K₂Cr₂O₇) is widely used as a primary standard in redox titrations because:
It is available in a highly pure form.
It is stable in air and does not absorb moisture.
Its molar mass is high, reducing weighing errors.
Its solutions can be prepared accurately by direct weighing.
In contrast, KMnO₄ is not a primary standard because it often contains impurities and decomposes on storage.