Chapter U5.7, Problem 2E

Interpretation Introduction

Interpretation: Three things to be named that are true to every combustion reaction.

Concept introduction: Combustion is a chemical reaction in which a compound or an element undergoes reaction with oxygen and releases energy in the form of light and heat. Combustion of covalent compounds comprising carbon and hydrogen produces carbon dioxide and water. The combustion of metallic substance produces metal oxide.

Answer to Problem 2E

Three things that are true of every combustion reactions are oxygen (reactant), heat and light (Light).

Explanation of Solution

Combustion reaction of methane and magnesium is as follows:

  $\begin{array}{l}{\text{CH}}_{\text{4}}(g)+2{\text{O}}_{\text{2}}(g)\to {\text{CO}}_{\text{2}}(g)+2{\text{H}}_{\text{2}}\text{O}\text{(}g\text{)}\text{+}\text{Heat}\text{+}\text{Light}\\ \text{2}\text{Mg}\text{(}s\text{)}\text{+}{\text{O}}_2(g)\to 2\text{MgO}\text{(}s\text{)}\text{+}\text{Heat}\text{+}\text{Light}\end{array}$

In combustion reactions, oxygen is always a reactant and other reactant is usually termed as fuel, in the above reactions, Methane $\left({\text{CH}}_{\text{4}}\right)$ and magnesium (Mg) are fuel.

In combustion reactions, heat and light are always produced. Heat is not a substance but it is included in the equation to keep track of energy changes.

Conclusion

In every combustion reaction, oxygen is a reactant and heat and light are always produced.