Ionisation constant of a weak base MOH, is given by the expression
`K_(b)=([M^(+)][OH^(-)])/([MOH])`
Values of ionisation constant of some weak bases at a particular temperature are given below :
`underset(K_(b))(Base)" "underset(5.4xx10^(-4))("Dimethylamine")" "underset(1.3xx10)(H_(2)O(l))" "underset(1.77xx10^(-9))("Pyridine")" "underset(1.77xx10^(-5))("Ammonia")`
Arrange the bases in decreasing order of the extent of their ionisation at equilibrium. Which of the above base is the strongest?

Explanation

The extent of ionisation depends upon the basic strength in turn is related to dissociation constant `(K_(2))` value. More the `K_(2)` value, stronger is the base. In the light of the avoce observations,
. Order of extent of ionisation at equilibrium point is.
. Diemthylamine is the strongset base since it is ionised to the maximum .