Sulfates are released during the combustion of fossil fuels primarily through the oxidation of sulfur present in the fuel. When fossil fuels are burned, sulfur is oxidized to sulfur dioxide (SO2), which can further react with oxygen to form sulfur trioxide (SO3). These reactions contribute to the formation of sulfuric acid (H2SO4) when SO2 or SO3 interacts with water vapor in the atmosphere. This process is closely linked to acid rain, as sulfuric acid dissociates into sulfate ions (SO4^2-) in solution, which can lower the pH of rainwater. The discussion highlights the importance of understanding the chemical reactions involved, including the reversible nature of SO2 dissolving in water and its subsequent oxidation to SO3. Additionally, automotive catalysts can facilitate the conversion of SO2 to SO3, contributing to sulfate emissions.