Question

Why is K₂Cr₂O₇ generally preferred over Na₂Cr₂O₇ in volumetric analysis although both are oxidising agents?

Answer 1

1. Potassium dichromate (K₂Cr₂O₇) is preferred because it is less deliquescent, making it easier to weigh accurately in volumetric analysis.
2. Sodium dichromate (Na₂Cr₂O₇) is more hygroscopic and absorbs moisture from the air, leading to errors in weight measurement.
3. K₂Cr₂O₇ is more stable and provides consistent results, which is crucial for precise titrations.
4. Both have similar oxidising power, but the practical aspects, like handling and weighing, favor K₂Cr₂O₇.

Hence, K₂Cr₂O₇ ensures higher accuracy and reproducibility in volumetric analysis than Na₂Cr₂O₇.