Final answer:
When dissolved in water, an acid dissociates into hydrogen ions (H+) and anions, while a base dissociates into hydroxyl ions (OH-) and cations.
Step-by-step explanation:
When an acid or a base is dissolved in water, they break down into ions. An acid dissociates into hydrogen ions (H+) and anions, while a base dissociates into hydroxyl ions (OH-) and cations. For example, a strong acid like hydrochloric acid (HCl) will dissociate completely in water to produce a high concentration of H+ and chloride ions (Cl-). Conversely, a strong base such as sodium hydroxide (NaOH) will completely dissociate in water to yield a high concentration of OH- and sodium ions (Na+).
In pure water, a tiny fraction of water molecules breaks down to form ions through a process in which water can act as both an acid and a base - this is known as the autoionization of water, represented by the equation: 2 H₂O → H3O+ + OH-. What's vital to note is that during the dissolution of acids and bases in water, the formation of ions is what leads to the characteristic properties of acidity or basicity in a solution.