The Solvent system(Self or Auto Ionization of Solvents)

 The most common concept of acids and bases is due to Cady and Elsey. Most of the solvents undergo auto-ionization and form cation and anions like water, regardless it contains protons or not.

For Examples: H2O, NH3, H2SO4,HNO3, 

POCl3, BrF3, N2O4, NOCl, CH3COOH,