Sulfuric acid (H2SO4) is not commonly used to prepare carbon dioxide (CO2) because the reaction between sulfuric acid and carbonates, which are the most common precursors for CO2 production, is relatively slow and inefficient. Alternatively, hydrochloric acid (HCl) is often used because it readily reacts with carbonates to release CO2 gas. The reaction between HCl and carbonates is faster, more complete, and produces a higher yield of CO2.