High Quality Content by WIKIPEDIA articles! The strength of an acid refers to its ability or tendency to lose a proton. There are very few strong acids. A strong acid is one that completely ionizes (dissociates) in water; in other words, one mole of a strong acid HA dissolves in water yielding one mole of H+ and one mole of the conjugate base, A?. Essentially none of the non-ionized acid HA remains. In contrast a weak acid only partially dissociates, and at equilibrium both the acid and the conjugate base are present in solution. Examples of strong acids are hydrochloric acid (HCl), hydroiodic acid (HI), hydrobromic acid (HBr), perchloric acid (HClO4), nitric acid (HNO3) and sulfuric acid (H2SO4). In water each of these essentially ionizes 100%. The stronger an acid is, the more easily it loses a proton, H+. Two key factors that contribute to the ease of deprotonation are the polarity of the H—A bond and the size of atom A, which determines the strength of the H—A bond. Acid strengths...