CaSO3↓ + SO2 + H2O -> Ca(HSO3)2 — Redox Reactions and Volumetric Analysis Chemistry Question

💡 Solution & Explanation

Step 1: Identify the initial state. Calcium sulfite, CaSO3↓, is an insoluble white precipitate. Step 2: Analyze the reaction with excess sulfur dioxide (SO2) and water. The SO2 dissolves in water to form sulfurous acid, which reacts with calcium sulfite to yield soluble calcium bisulfite (Ca(HSO3)2). Step 3: Since the insoluble precipitate is converted into a soluble species and dissolves completely, this is a precipitate dissolution reaction (type B). Thus, the correct option is (b).