A descaling agent or chemical descaler is a chemical substance used to remove limescale from metal surfaces in contact with hot water, such as in boilers, water heaters, and kettles. Descaling agents are typically acidic compounds such as hydrochloric acid that react with the alkaline carbonate compounds present in the scale, producing carbon dioxide gas and a soluble salt. Strongly acidic descaling agents are often corrosive to the eyes and skin.