Simulations solve 200-year-old ionic mystery of water

State-of-the-art simulations have solved a conundrum that scientists have puzzled over for around two centuries – the mystery of why positive hydronium ions diffuse almost twice as fast as their negative hydroxide counterparts in water. In pure water, hydroxide and hydronium ions are present in equal quantities. Their motion is fundamental to chemical reactions in water, as well as acid-base chemistry. They naturally form because water molecules react with each other in a self-ionisation process caused by proton transfer. Water molecules deprotonate, or lose the nucleus of one of their hydrogen atoms, to become hydroxide (OH^-) anions.