Preparation of Bases Bases can be prepared by the following methods.Methods of preparation of bases 1. By the direct union of a metal with oxygen Some metals when heated in air or oxygen form the oxides of the metals.These oxides when dissolves in water make the hydroxides of metals.Na2O + H2O → 2NaOHK2O + H2O → 2KOHCaO + H2O → … [Read more...] about Preparation of Bases