Relative strength of acids and Bases
In practice 
is used to define the strength only of those acids that are weaker than 
and 
is used to define the strength of only those bases that are weaker than 
. For two weak acids 
and 
of ionisation constant 
and 
respectively at the same concentration 
, we have,
Similarly, relative strengths of any two weak bases at the same concentration are given by the ratio of the square-roots of their dissociation constants. i.e.,
