Once you have a feeling for the extent of reaction of the various species with water, it is possible to predict the
major species (A major species is present in relatively high concentration (>10% of the concentration of other species)) when equilibrium is established. In general
- for molecular (uncharged) weak acids and bases, the weak acid (or base) is the major species in solution. The conjugate, H3O+ and OH– are minor species in solution.
- for strong acids and bases, the conjugate is one of the major species in solution.
For strong acids H3O+ is also a major species.
For strong bases OH– is also a major species.
One member of every conjugate pair is charged and is used as a salt. Usually the counter-ion does not react with water.
Cationic acids are often dissolved as their chloride.
Anionic acids and bases are often dissolved as their sodium or potassium salt.
Chlorides and potassium and sodium salts are strong electrolytes.
The counter-ions Na+(aq), K+(aq) and Cl–(aq) are thus major species in these solutions.
The other major species depend on the acid (or base) strength of the ion which is pH active.