The pH of a 0.30-M solution of a weak base is 10.66 at . The of the given base has to be calculated.
Strong base and weak base:
Strong base dissociates into its constituent ions fully. It produces more of hydroxide ions while dissolved in water. Weak bases partially dissociates into its constituent ions.
According to Bronsted-Lowry, strong base is a good proton acceptor whereas weak base is a poor proton acceptor
Since, the ionization of a weak base is incomplete; it is treated in the same way as the ionization of a weak acid.
The ionization of a weak base is given by the below equation.
The equilibrium expression for the ionization of weak base will be,
is base ionization constant,
is concentration of hydroxide ion
is concentration of conjugate acid
is concentration of the base
The of a solution is defined as the negative base-10 logarithm of the hydroxide ion concentration. scale is analogous to pH scale.
Relationship between and
is similar to . The only difference is that in the concentration of hydroxide ion is used as a scale while in , the concentration of hydronium ion is used.
The relationship between the hydronium ion concentration and the hydroxide ion concentration is given by the equation,
As and are opposite scale, the total of both has to be equal to 14.