Q4.6P - Chemistry: Molecular Nature Of Matter And Change

Question

Question: Which of the following scenes best represents a volume from a solution of magnesium nitrate?

Step-by-Step Solution

Answer

Answer 

Scene (B) best represents a volume from a solution of magnesium nitrate. 

Step 1: Dissociation of ionic compounds in aqueous solution

When an ionic compounds dissolve in the aqueous medium, it dissociates into its ions, since, they form an ionic bond. When it breaks, ions contain some positive or negative charge that depends upon the valency of that atom.

Step 2: Dissociation of magnesium nitrate

In an aqueous medium,$\mathit{M}\mathit{g}\mathbf{(}{\mathbf{NO}}_{\mathbf{3}}{\mathbf{)}}_{\mathbf{2}}$  is dissociated as $\mathit{M}{\mathit{g}}^{\mathbf{2}\mathbf{+}}$ and $\mathit{N}{{\mathbf{O}}_{\mathbf{3}}}^{\mathbf{-}}$ ions which means it produces one ion of $\mathit{M}{\mathit{g}}^{\mathbf{2}\mathbf{+}}$ and two ions of data-custom-editor="chemistry" $\mathit{N}{{\mathbf{O}}_{\mathbf{3}}}^{\mathbf{-}}$ in the solution, therefore, the number of anions is twice the number of a cation.

                            $\mathit{M}\mathit{g}\mathbf{(}\mathbf{N}{\mathbf{O}}_{\mathbf{3}}{\mathbf{)}}_{\mathbf{2}}\mathbf{\left(}\mathit{s}\mathbf{\right)}\mathbf{\to }\mathit{M}{\mathit{g}}^{\mathbf{2}\mathbf{+}}\mathbf{\left(}\mathit{a}\mathit{q}\mathbf{\right)}\mathbf{+}\mathbf{2}\mathit{N}{{\mathbf{O}}_{\mathbf{3}}}^{\mathbf{-}}\mathbf{\left(}\mathit{a}\mathit{q}\mathbf{\right)}$

In scene (B) there are two  ions and four  anions Hence, scene (B) best represents a volume from a solution of magnesium nitrate.