An inorganic compound W undergoes the following reactions: gathered W+ Na ₂ CO ₃ O ₂ / heat X+ H ⁺ Y_ (s) Y(a q)+ KCl ( aq ) Z_ (S) gathered Z appears in the form of orange crystals and is used as an oxidising agent in acid medium. Identify the compound W.

Step-by-step solution

The reaction sequence describes the industrial preparation of potassium dichromate from chromite ore. The compound W is chromite ore, FeCr ₂ O ₄ . In the first step, chromite ore reacts with sodium carbonate in the presence of air (oxygen) to form sodium chromate: 4 FeCr ₂ O ₄ + 8 Na ₂ CO ₃ + 7 O ₂ 8 Na ₂ CrO ₄ + 2 Fe ₂ O ₃ + 8 CO ₂ Here, X is Na ₂ CrO ₄ . Upon acidification with H ⁺ , sodium chromate converts to sodium dichromate: 2 Na ₂ CrO ₄ + 2 H ⁺ Na ₂ Cr ₂ O ₇ + 2 Na ⁺ + H ₂ O The resulting sodium dichromate