Chapter 4, Problem 121AP

Interpretation Introduction

Interpretation:

The methods to separate the cations and anions in the given solutions are to be explained.

Concept introduction:

As per the solubility principle, based upon the solubility, and the ionic products of compounds, certain compounds get precipitated in certain solutions.

In a solution, precipitation reactions happen when cations and anions combine to form an insoluble ionic solid known as a precipitate.

An insoluble solid product that separates from a solution in achemical reaction is called as precipitate.

The reaction in which the precipitate gets formed is known as precipitation reaction.

Answer to Problem 121AP

Solution:

a) ${\text{Ba(NO}}_{\text{3}}{\text{)}}_{\text{2}}\left(aq\right){\text{ + Na}}_{\text{2}}{\text{SO}}_{\text{4}}\left(aq\right)\to {\text{ BaSO}}_{\text{4}}\left(s\right){\text{ + 2NaNO}}_{\text{3}}\left(aq\right)$

b) ${\text{Mg(NO}}_{\text{3}}{)}_2\left(aq\right){\text{ + K}}_{\text{2}}{\text{CO}}_{\text{3}}\left(aq\right)\to {\text{ MgCO}}_{\text{3}}\left(s\right){\text{ + 2KNO}}_{\text{3}}\left(aq\right)$

c) $\text{KBr}\left(aq\right){\text{ + AgNO}}_{\text{3}}\left(aq\right)\to \text{ AgBr}\left(s\right){\text{ + KNO}}_3\left(l\right)$

d) ${\text{2K}}_{\text{3}}{\text{PO}}_{\text{4}}\left(aq\right){\text{ + 3Ca(NO}}_{\text{3}}{)}_2\left(aq\right)\to {\text{ Ca}}_{\text{3}}{{\text{(PO}}_{\text{4}}\text{)}}_{\text{2}}\left(s\right){\text{ + 6KNO}}_3\left(aq\right)$

e) ${\text{Na}}_{\text{2}}{\text{CO}}_{\text{3}}\left(aq\right){\text{ + Ca(NO}}_{\text{3}}{)}_2\left(aq\right)\to {\text{ CaCO}}_{\text{3}}\left(s\right){\text{ + 2NaNO}}_3\left(aq\right)$

Explanation of Solution

a) ${\text{NaNO}}_3$ and ${\text{Ba(NO}}_{\text{3}}{\text{)}}_{\text{2}}$

A soluble sulphate salt, like sodium sulfate ${\text{Na}}_{\text{2}}{\text{SO}}_{\text{4}}$, if added to a mixture of ${\text{NaNO}}_3$ and ${\text{Ba(NO}}_{\text{3}}{\text{)}}_{\text{2}}$, will cause ${\text{BaSO}}_{\text{4}}$ to be precipitatedwhile the sodium ions stay in solution.

The reaction is as follows:

${\text{Ba(NO}}_{\text{3}}{\text{)}}_{\text{2}}\left(aq\right){\text{ + Na}}_{\text{2}}{\text{SO}}_{\text{4}}\left(aq\right)\to {\text{ BaSO}}_{\text{4}}\left(s\right){\text{ + 2NaNO}}_{\text{3}}\left(aq\right)$

b) ${\text{Mg(NO}}_3{)}_2$ and ${\text{KNO}}_{\text{3}}$

Potassium carbonate ${\text{K}}_{\text{2}}{\text{CO}}_{\text{3}}$, if added to a mixture of ${\text{Mg(NO}}_3{)}_2$ and ${\text{KNO}}_{\text{3}}$, will cause precipitation of the magnesium cations. The remaining ions of potassium will leave the solution.

The following chemical reaction takes place:

${\text{Mg(NO}}_{\text{3}}{)}_2\left(aq\right){\text{ + K}}_{\text{2}}{\text{CO}}_{\text{3}}\left(aq\right)\to {\text{ MgCO}}_{\text{3}}\left(s\right){\text{ + 2KNO}}_{\text{3}}\left(aq\right)$

c) $\text{KBr}$ and ${\text{KNO}}_{\text{3}}$

Silver nitrate ${\text{AgNO}}_{\text{3}}$, when added to a mixture of $\text{KBr}$ and ${\text{KNO}}_{\text{3}}$, causes precipitation of the bromide ions. The remaining nitrate ions leave the solution.

The following chemical reaction takes place:

$\text{KBr}\left(aq\right){\text{ + AgNO}}_{\text{3}}\left(aq\right)\to \text{ AgBr}\left(s\right){\text{ + KNO}}_3\left(l\right)$

d) ${\text{K}}_{\text{3}}{\text{PO}}_{\text{4}}$ and ${\text{KNO}}_{\text{3}}$

Calcium nitrate ${\text{Ca(NO}}_{\text{3}}{)}_2$, when added to a mixture of ${\text{K}}_{\text{3}}{\text{PO}}_{\text{4}}$ and ${\text{KNO}}_{\text{3}}$, causes precipitation of the phosphate ions. The remaining nitrate ions stay the solution.

The following chemical reaction takes place:

${\text{2K}}_{\text{3}}{\text{PO}}_{\text{4}}\left(aq\right){\text{ + 3Ca(NO}}_{\text{3}}{)}_2\left(aq\right)\to {\text{ Ca}}_{\text{3}}{{\text{(PO}}_{\text{4}}\text{)}}_{\text{2}}\left(s\right){\text{ + 6KNO}}_3\left(aq\right)$

e) ${\text{Na}}_{\text{2}}{\text{CO}}_{\text{3}}$ and ${\text{NaNO}}_{\text{3}}$

Calcium nitrate ${\text{Ca(NO}}_{\text{3}}{)}_2$, when added to a mixture of ${\text{Na}}_{\text{2}}{\text{CO}}_{\text{3}}$ and ${\text{NaNO}}_{\text{3}}$, causes precipitation of the carbonate ions. The remaining nitrate ions stay in the solution.

The following chemical reaction takes place:

${\text{Na}}_{\text{2}}{\text{CO}}_{\text{3}}\left(aq\right){\text{ + Ca(NO}}_{\text{3}}{)}_2\left(aq\right)\to {\text{ CaCO}}_{\text{3}}\left(s\right){\text{ + 2NaNO}}_3\left(aq\right)$