Question

What is the range of pH value of salt formed by a-
(A) Weak acid and strong base
(B) Strong acid and strong base
(C) The soil in a field is highly acidic. List any two materials which can be added to this soil to reduce its acidity. Give the reason for your choice.

Answer 1

Hint: The pH of a certain solution is often helpful to be able to predict the effect of a salt solution. When a salt solution acidic or basic depends on several guiding principles like salts from strong bases and strong acids, salts that are from strong bases and weak acids, salts of weak bases and strong acids, salts from a weak base and weak acid.

Complete step by step solution:
(A) The range of pH value of salt formed by weak acid and strong base:
Weak acid will not neutralize strong acid completely. So, the resultant mixture will be basic. The salts which are a weak acid and strong base do hydrolyze and the pH of the salt will be greater than 7. The cation of salt will be from a strong base either the alkaline or alkaline earth metals which are dissociated into an ion and not affect the ${{H}^{+}}$
(B) The range of pH value of salt formed by strong acid and strong base:
The salts are from a strong acid and strong base do not hydrolyze and the resulting salt pH will remain 7. The anion in the salt form's strong base does not attract the ${{H}^{+}}$ from the water.
(C) If the soil is highly acidic this can be neutralized by adding a basic substance. CaO and calcium hydroxide ($Ca{{(OH)}_{2}}$) which can be added to the soil to reduce acidity.

Note: Salts are reacting with water to produce ${{H}_{3}}{{O}^{+}}$ and $O{{H}^{-}}$ , when salts are placed in water is known as a hydrolysis reaction. The pH range of salts based on the strength of ions acts as an acid or base. There are many possibilities due to the varying structures of salts when water and salts react.