Although sodium dichromate () exhibits greater aqueous solubility and is extensively utilized as a p — d and f Block Elements Chemistry Question
Question
Although sodium dichromate ($Na_2Cr_2O_7$) exhibits greater aqueous solubility and is extensively utilized as a primary oxidising agent in organic chemistry, potassium dichromate ($K_2Cr_2O_7$) is universally preferred exclusively as a primary standard in precision volumetric analysis. Why?
💡 Solution & Explanation
To be used as a primary standard in volumetric analysis, a substance must be incredibly stable and strictly non-hygroscopic so that it can be weighed with exact precision without absorbing atmospheric moisture. Sodium dichromate ($Na_2Cr_2O_7$) is deliquescent/hygroscopic, making accurate weighing impossible. $K_2Cr_2O_7$ does not absorb moisture, making it ideal.