Question

The $p{K_b}$ of a weak base, is $4.78$ . The $p{K_a}$ of weak acid is $4.80$ . What is the pH of an aqueous solution of the corresponding salt will be.

Answer 1

Weak acids and bases are just in part ionized in their solutions, though strong acids and bases are totally ionized when disintegrated in water. If the pH of both weak acid and base is equal, then the pH will be neutral.

Complete step by step solution:
We know, the formula for hydrolysis of salt
= $\sqrt {\dfrac{{{K_w}}}{{{K_a}{K_b}}}}$
Or
= pH = $7 - \dfrac{1}{2}[p{K_w} + p{K_a} - p{K_b}]$
Where ${K_w}$ = hydrolysis constant,
${K_a}$ = ionization constant for weak acid,
${K_b}$ = ionization constant for weak base
Now, let’s put the values in the formula
pH = $\dfrac{1}{2}(14 + 4.80 - 4.78)$
= $7.01.$

Additional Information:
- Regardless of whether an acid totally ionizes in water relies upon the distribution of the electrons in a chemical bond. At the point when two particles in a bond have almost similar electronegativity values, the electrons are uniformly shared and invest equivalent measures of energy related with one or the other ions.
When the weak base is broken up in a solution, a piece of the weak base separates into hydroxide anions and the important form acid, and another part remains un dissociated inside the arrangement. The ionization of a weak base is typically a kind of balance measure in which a chemical balance is set up inside the arrangement between the concentration of the base and its constituent particles.

Note:
Remember that the form acid of a weak base will quite often be a weak acid. Essentially, the form base of a weak acid will go about as a feeble base.