When KHSO4 is added into a concentrated solution of H2SO4, the acidity of the solution: — p Block Elements Chemistry Question

💡 Solution & Explanation

Step 1: Concentrated sulfuric acid (H2SO4) undergoes self-ionization (autoprotolysis): 2H2SO4 <=> H3SO4^+ + HSO4^-. Step 2: Adding potassium bisulfate (KHSO4) introduces a large concentration of HSO4^- ions (bisulfate/hydrogen sulfate ions), which is the conjugate base of H2SO4. Step 3: By Le Chatelier's principle, the common-ion effect of HSO4^- shifts the autoprotolysis equilibrium to the left, decreasing the concentration of the highly acidic H3SO4^+ ions and thus decreasing the overall acidity of the solution (option b).