They are usually classified on the basis of concentration and on its acidity.
Classification based on the Concentration
The concentration of the base depends upon the amount of base dissolved in water.
It is of two types i.e. Concentrated and Dilute base.
Concentrated Base: An aqueous solution which has a relatively high percentage of the base is a concentrated base.
For e.g. Concentrated sodium hydroxide, concentrated potassium hydroxide, concentrated ammonium hydroxide etc.
Diluted Base: An aqueous solution which has a relatively low percentage of the base is a dilute base. For e.g. dilute sodium hydroxide, diluted potassium hydroxide, dilute ammonium hydroxide, etc.
Classification based on the Acidity of the Base.
The acidity of a base depends on the number of hydroxyl ions it contains. It also depends on the number of hydrogen ions with which a base can combine as one hydrogen ion combines with one hydroxyl ion.
It is usually of three types Monoacidic base, Diacidic base, and Triacidic base.
Monoacidic base: It is a base that consists only one hydroxyl ion and only combines with one hydrogen ion.
For e.g. NaOH, KOH, NH4OH, etc.
NaOH(aq) + HCl(aq) <—> NaCl(aq) + H2O(l)
Diacidic base: It is a base that contains two hydroxyl ions and combines with two hydrogen ions.
For e.g. Mg(OH)2, Fe(OH)2, Zn(OH)2, etc.
Ca(OH)2(aq) + 2HCl(aq) <—> CaCl2(aq) + 2H2O(l)
Triacidic base: It is a base that has three hydroxyl ions and combines with three hydrogen ions.
For e.g. Aluminium Hydroxide.
Al(OH)3(aq) + 3HCl(aq) <—> AlCl3(aq) + 3H2O(l)
