Limitations of Bronsted Lowry Concept
(i) The protonic definition cannot be used to explain the reactions occuring in non-protonic solvents such as COCl2, SO2, N2O4, etc.
(ii) It cannot explain the reactions between acidic oxides like etc and the basic oxides like etc which take place even in the absence of the solvent e.g.,
There is no proton transfer in the above example.
(iii) Substances like BF3, AlCl3 etc, do not have any hydrogen and hence cannot give a proton but are known to behave as acids.
Table: Conjugate acid-base pairs
|(Perchloric acid)||Increasing order of acidic strength||(Perchlorate ion)||Increasing order of basic strength|
|(Sulphuric acid)||(Hydrogen sulphate ion)|
|(Hydrogen chloride)||(Chloride ion)|
|(Nitric acid)||(Nitrate ion)|
|(Hydrogen sulphate ion)||(Sulphate ion)|
|(Ortho phosphoric acid)||(Dihydrogen phosphate ion)|
|(Acetic acid)||(Acetate ion)|
|(Carbonic acid)||(Hydrogen carbonate ion)|
|(Hydrogen sulphide)||(Hydrogen sulphide ion)|
|(Hydrogen cyanide)||(Cyanide ion)|
|(Ethyl alcohol)||(Ethoxide ion)|