Chapter 21, Problem 2PS

Interpretation Introduction

Interpretation: Examples for two acidic oxides has to be given.  Equations illustrating the formation of each oxide from its component elements should be written.

Concept introduction: Oxides are formed by reaction of metal with oxygen.  An acidic oxide is an oxide that shows acidic properties in solution.  If an element E belongs to group $\text{VIA}$of periodic table, then the general reaction of formation of oxide is:

  $\text{E}\left(\text{s}\right){\text{+ O}}_{\text{2}}\left(\text{g}\right)\to {\text{EO}}_2\left(g\right)$

Acidic oxides on reaction with water form an acid.  This is a characteristic property of acidic oxides and thus illustrates its acidic behavior.  Acidic oxides are mostly oxides of group $\text{VA}$and $\text{VIA}$elements.  Thus, acidic oxides are generally oxides of non-metals and they react with water to form acids. The general reaction of a non-metal oxide with water is as follows:

  ${\text{EO}}_{\text{2}}\left(\text{g}\right){\text{+H}}_{\text{2}}\text{O}\left(\text{l}\right)\to {\text{HEO}}_{\text{3}}\left(\text{aq}\right){\text{+ HEO}}_{\text{2}}\left(\text{aq}\right)$

Here, E is any element of group $\text{VA}$or $\text{VIA}$of the periodic table.

Answer to Problem 2PS

The two example of acidic oxides are and.

The equation illustrating the formation of each oxide from its elements is:

For${\text{NO}}_{\text{2}}$,

    

For${\text{SO}}_{\text{3}}$,

    

The equation that illustrates the acidic character of each oxide is:

For${\text{NO}}_{\text{2}}$,

    

For${\text{SO}}_{\text{3}}$,

    

Explanation of Solution

Acidic oxides are generally oxides of non-metals of group $\text{VA}$and $\text{VIA}$metals.  The two examples of acidic oxide are ${\text{NO}}_{\text{2}}$ and${\text{SO}}_{\text{3}}$.

Both the oxides are formed in the presence of excess oxygen.  Nitrogen dioxide is formed by reaction of nitrogen monoxide formed by reaction of nitrogen with oxygen, with atmospheric oxygen. Sulfur trioxide is formed by the reaction of sulfur dioxide with oxygen.

Thus, the balanced chemical equation is:

• For${\text{NO}}_{\text{2}}$,

    $\begin{array}{l}{\text{N}}_{\text{2}}\left(\text{g}\right){\text{+ O}}_{\text{2}}\left(\text{g}\right)\to \text{2NO}\left(\text{g}\right)\\ \text{2NO}\left(\text{g}\right){\text{+O}}_{\text{2}}\left(\text{g}\right)\to {\text{2NO}}_{\text{2}}\left(\text{g}\right)\end{array}$

• For${\text{SO}}_{\text{3}}$,

    $\begin{array}{l}\text{S}\left(\text{g}\right){\text{+O}}_{\text{2}}\left(\text{g}\right)\to {\text{SO}}_{\text{2}}\left(\text{g}\right)\\ {\text{SO}}_{\text{2}}\left(\text{g}\right)\text{+}\frac{\text{1}}{\text{2}}{\text{O}}_{\text{2}}\left(\text{g}\right)\to {\text{SO}}_{\text{3}}\left(\text{g}\right)\end{array}$

The stoichiometric coefficients are multiplied with the compounds in the chemical equation to have an equal number of atoms on both sides of the equation.  Since oxygen is present as ${\text{O}}_{\text{2}}$ and nitrogen is present as ${\text{N}}_{\text{2}}$ in the reaction, hence the stoichiometric coefficient of non-metal oxide, $\text{NO}$ is $2$. Similarly, the equation for the formation of sulfur trioxide is balanced by multiplying ${\text{O}}_{\text{2}}$ with a stoichiometric coefficient of $\frac{1}{2}$.

A major property of acidic oxide that illustrates its acidic character is that the acidic oxides on reaction with water produce acids. Thus, the equation illustrating the acidic character of each oxide is the reaction of its oxide with water.

For${\text{NO}}_{\text{2}}$,

    ${\text{2NO}}_{\text{2}}\left(\text{g}\right){\text{+H}}_{\text{2}}\text{O}\left(\text{l}\right)\to {\text{HNO}}_{\text{3}}\left(\text{aq}\right){\text{+HNO}}_{\text{2}}\left(\text{aq}\right)$

For${\text{SO}}_{\text{3}}$,

    ${\text{SO}}_{\text{3}}\left(\text{g}\right){\text{+H}}_{\text{2}}\text{O}\left(\text{l}\right)\to {\text{H}}_{\text{2}}{\text{SO}}_{\text{4}}\left(\text{aq}\right)$

Thus, both ${\text{NO}}_{\text{2}}$ and ${\text{SO}}_{\text{3}}$ on reaction with water produces corresponding acids.  Nitrogen dioxide produces nitrous acid and nitric acid on reaction with water while sulfur trioxide produces sulfuric acid, which illustrates that these oxides are acidic in nature.

Conclusion

Acidic oxides are generally oxides of non-metals. The two example of acidic oxides are and .

The equation illustrating the formation of each oxide from its elements is:

For${\text{NO}}_{\text{2}}$,

    

For${\text{SO}}_{\text{3}}$,

    

A major property of acidic oxide that illustrates its acidic character is that the acidic oxides on reaction with water produce acids. Thus, the equation illustrating the acidic character of each oxide is the reaction of its oxide with water.

For${\text{NO}}_{\text{2}}$,

    

For${\text{SO}}_{\text{3}}$,