What is solubilityy product? Explain the common ion effect on solubility of ionic salts.

Explanation

Solubility product `(K_(sp))` : The product of the concentrations of the cation and the anion in a saturated solution of a salt at room temperature is called solubility product `(K_(sp))`
`K_(sp)=[M^(n+1)][A^(n-1)]`
Significance of solubility product in chemical analysis :
In any solution of a salt, if the product of `[M^(n+1)] and [A^(n-) ]` is greater than the solubility product `(K_(sp))` of the salt, then only the salt gets precipitated. For example,
(i) If the product of `[Cu^(2+)] & [S^(-2)]` in the II group (in presence of acid) of chemical analysis exceeds the value of. `K_(sp)` of Cus, then only cus will be precipitated in the group. Similar argument applies to other metal ions in the group namely `(Cd^(2+),Bi^(3+),Hg^(2+),Sb^(2+)` etc)
(ii) .If the product of `[Zn^(2+)] and [S^(2-)]` in ammonical medium in IV group of chemical analysis exceeds the value of `K_(sp)` of Zns, it will be precipitated. Similar arguments apply to `Mn^(2+),Ni^(2+)` etc.

`to` Given salt `CH_(3)COONa` is obtained by the reactio of weak acid `(CH_(3)COOH)` and strong base (NaOH).
`to` The ionisation `CH_(3)COONa` as follows
`CH_(3)COONa hArr CH_(3)COO^(-)+Na^(+)`
`to` the above salt undergo anionic hydrolysis
`CH_(3)COO^(-)+H_(2)O hArr CH_(3)COOH+OH^(-)`
`:.` The aq solution of salt is basic due to greater `OH^(-)` ion concentration than `H^(+)` ion concentration.
`:. P^(H) gt 7`
`to` given salt `NH_(3)cl` is obtained by the reaction of strong acid (HCl) and weak base `(NH_(4)OH)`.
`to` The ionisation of `NH_(4)Cl` is obtained by the reaction of strong acid (HCl) and weak base `(NH_(4)OH)`.
`to` The ionisatio of `NH_(4)Cl` as follows
`nH_(4)^(+)+Cl^(-) hArr NH_(4)Cl`
`to` The above salt under goes catioric hydrolysis.
`NH_(4)^(+)+H_(2)O hArr NH_(4)OH+H^(+)`
`:.` The equation solution of salt is acidic due to greater `H^(+)` concentration than `OH^(-)` ion concen .tration.
`:. PH lt 7`
Common ion effect on solubility of ionic salts
The common ion effect is used for almost complete precipitation of a particular ion as its spar ingly soluble salt, with every low value of solubility product for gravimetric estimation. Thus we can precipitate silver ion as silver chloride, ferric ion as its hydroxide (or hydrated ferric oxide) and barium ion as its sulphate for quantitative estimations.