# Question #ed5f9

Jan 12, 2016

Oxirreduction, or combustion.

#### Explanation:

Reactions of the type

$4 M + {O}_{2} \rightarrow 2 {M}_{2} O$
$2 M + {O}_{2} \rightarrow 2 M O$
$4 M + 3 {O}_{2} \rightarrow 2 {M}_{2} {O}_{3}$

Where $M$ is a metal are oxirreduction (or redox) reactions since the metals goes from having a $0$ net charge to a positive one (it's being oxidized) whereas Oxygen goes from having a $0$ net charge to $- 2$, being reduced.

Which of the equations will happen, will depend on the metal. But reactions of this type can happen with other compounds, including, for example the combustion of coal

$C + {O}_{2} \rightarrow C {O}_{2}$

The combustion of hydrocarbons in general

$2 {C}_{x} {H}_{y} + \left(4 x + y\right) {O}_{2} \rightarrow 2 x C {O}_{2} + y {H}_{2} O$

(Whereas any present oxygen may or may not become oxygen gas, and nitrogen or sulfur will go to an oxide depending on the amount of oxygen available among other things).