During the vital first step in the preparation of potassium dichromate from chromite ore, why is qui — d and f Block Elements Chemistry Question

💡 Solution & Explanation

In the commercial preparation of $K_2Cr_2O_7$, finely powdered chromite ore ($FeCr_2O_4$) is roasted with $Na_2CO_3$ in a reverberatory furnace with free exposure to air. Quicklime ($CaO$) is specifically added to this mixture because it keeps the mass highly porous. This porosity allows vital $O_2$ gas to permeate the entire mass, preventing the mixture from melting/fusing, thus maximizing the oxidation yield of yellow sodium chromate.