-The product of the concentration of ions of an electrolyte in a saturated solution at a particular temperature.
-It is denoted by .
-The product of concentration of ions.
-It is denoted by
At a given temperature if;
i) , the solution is said to be unsaturated i.e. more solute can be dissolved in the solution.
ii) , the solution is saturated, no precipitation can take place.
iii) , the solution is said to be supersaturated, precipitation takes place.
-Encountering many precipitation reactions, like White ppt of is formed when reacts with
These compounds like are insoluble compounds however they are sparingly soluble salts. These undissolved salts goes ionization eg:
The equilibrium constant,
or, is the solubility product.
Let be sparingly soluble salt, at equilibrium,
Now, for this system is given as,
i) Calcium phosphate
(s is for )
ii) Bismuth Sulphide :
-Solubility product principle is valid only for saturated solutions in which total concentration of ions is no more than about .
-By the addition of the salt, , the concentration of increases. Therefore, according to Le Chatelier's principle, the equilibrium will shift to the left, thereby decreasing the concentration of ions. Of that, the degree of dissociation of will be reduced.
-A salt of a weak acid is added to a solution of the acid itself, the dissociation of the acid is diminished further.
-The addition of one of the products of dissociation (example: acetate ion), supplied by the largely dissociated salt (example: sodium acetate)pushes the equilibrium to the left. In other words, the dissociation of acetic acid is suppressed. Similarly, the addition of hydrogen ions furnished by the addition of a largely dissociated acid such as hydrochloric acid , also suppresses the dissociation of acetic acid.
-Thus, the common ion effect is the "suppression of the dissociation of a weak acid or a weak base on the addition of its own ions".
a. Salts of strong acid and strong base do not go hydrolysis. E.g: .
b. Salts of weak acid and strong base gives basic solution. E.g: .
c. Salts of weak bases and strong acids yield slightly acidic solution. E.g:
d. Salts of weak acids and weak bases gives neutral, basic or acidic depending on the relative hydrolysis of the anions and the cations.