Chapter 9, Problem 124A

Interpretation Introduction

Interpretation:

The balanced chemical equation for the reaction of aluminium with oxygen to produce aluminum oxide needs to be determined.

Concept introduction:

For balancing an equation first the skeleton equation should be written. After that count the atoms of both side, count each polyatomic ion as a single element. Find the correct coefficient and placed them in front of the atoms. In a balanced chemical equation, same atoms should be equal in both sides of the reaction arrow.

Answer to Problem 124A

The balanced equation is as follows:

$\text{4Al}\left(\text{s}\right){\text{+3O}}_2\left(\text{g}\right)\to 2{\text{Al}}_{\text{2}}{\text{O}}_{\text{3}}\left(\text{s}\right)$

Explanation of Solution

Write the word equation for the reaction of aluminium with oxygen.

$\text{Aluminium}\left(\text{s}\right)\text{+Oxygen}\left(\text{g}\right)\to \text{Aluminium}\text{oxide}\left(\text{s}\right)$

Now, write the skeleton equation:

$\text{Al}\left(\text{s}\right){\text{+O}}_2\left(\text{g}\right)\to {\text{Al}}_{\text{2}}{\text{O}}_{\text{3}}\left(\text{s}\right)$

In reactant side number of Al atom is 1 and oxygen atom is 2 while in product side number of Al atom is 2 and oxygen atom is 3. To balance Al and O in both sides, give coefficient 4 to Al and 3 to ${\text{O}}_2$. Similarly, give coefficient 2 to ${\text{Al}}_{\text{2}}{\text{O}}_{\text{3}}$.

Therefore, the balance equation is as follows:

$\text{4Al}\left(\text{s}\right){\text{+3O}}_2\left(\text{g}\right)\to 2{\text{Al}}_{\text{2}}{\text{O}}_{\text{3}}\left(\text{s}\right)$

Conclusion

A balanced chemical equation means the number of atoms on both the product side participates and the reactant side is identical.