Question

When ammonium chloride and ammonium hydroxide are added to a solution containing both $A{{l}^{3+}}$ and $C{{a}^{2+}}$ ions, which ion is precipitated first and why?

Answer 1

Hint: -Ammonium chloride is an inorganic compound with an $N{{H}_{4}}Cl$ structure and a white crystalline salt that is highly soluble in water. Ammonium chloride solutions are slightly acidic. Ammonium hydroxide, also known as ammonia powder, ammonia solution is an ammonia solution in powder. It can be denoted by $N{{H}_{3}}\left( aq \right)~$ symbols.

Complete step by step answer:
An ion compound is precipitated from the solution when the concentration of its cation and anion reaches its solubility level.
As ammonium chloride and ammonium hydroxide are added to the solution containing $A{{l}^{3+}}$ and $C{{a}^{2+}}$ ions, $A{{l}^{3+}}$gets first precipitated as $Al{{\left( OH \right)}_{3}}$. The solubility product of $Al{{\left( OH \right)}_{3}}$ is way less than the solubility product of $Ca{{\left( OH \right)}_{2}}$. $N{{H}_{4}}Cl$ suppress the dissociation of$N{{H}_{4}}OH$ which ends in very low hydroxide ion concentration. At such an occasional hydroxide concentration, the ionic product of $Al{{\left( OH \right)}_{3}}$ exceeds its solubility product which ends in precipitation.
Solubility is known as the maximum volume of solution that can be dissolved in an equilibrium solvent.
The constant of the solubility substance (${{K}_{sp}}$) represents the relationship between a solid in a solution and its constituent ions.
Solubility equilibrium is a type of dynamic equilibrium that occurs when a solid-state chemical compound with a solution of that compound is in chemical equilibrium. The solid can dissolve unchanged, either with dissociation or with chemical reaction to another solution component, such as acid or alkaline.
In the salt analysis, $N{{H}_{4}}Cl$ is added in appropriate quantity before the addition of $N{{H}_{4}}OH$, otherwise the higher group cations may be precipitated in group III. (Reason: $N{{H}_{4}}Cl$ is a solid electrolyte that decomposes completely. Although the $N{{H}_{4}}OH$ is a weak base, it does not ionise completely.)

Note: -$C{{a}^{2+}}$ ions are precipitated as $CaC{{O}_{3}}$ with the reagent ammonium carbonate + ammonium hydroxide + ammonium chloride.
-As ammonium chloride is added to the ammonium hydroxide solution, the activity of changing or exchanging ions takes place. The reaction is termed a double displacement reaction.