What is the chemical equation to show the combustion reaction of ethanol?

${\text{C}}_2{\text{H}}_6\text{O(l)}+{\text{O}}_2\text{(g)}$$\to$${\text{CO}}_2\left(\text{g}\right)+{\text{H}}_2\text{O(l})$

Balance the Equation:

Balance the $\text{C}$ and $\text{H}$ first. There are $2$ carbon atoms on the left side, and $1$ carbon atom on the right side. There are $6$ hydrogen atoms on the left side and $2$ hydrogen atoms on the right side.

Add a coefficient of $2$ in front of the carbon dioxide, and a coefficient of $3$ in front of the water.

${\text{C}}_2{\text{H}}_6\text{O(l)}+{\text{O}}_2\text{(g)}$$\to$$2{\text{CO}}_2\left(\text{g}\right)+3{\text{H}}_2\text{O(l})$

We now have equal numbers of $\text{C}$ and $\text{H}$ atoms on both sides. However, the $\text{O}$ is not balanced.

We have $7$ $\text{O}$ atoms on the right side, and $3$ on the left side. Place a coefficient of $3$ in front of the ${\text{O}}_2$ on the left side.

${\text{C}}_2{\text{H}}_6\text{O(l)}+3{\text{O}}_2\text{(g)}$$\to$$2{\text{CO}}_2\left(\text{g}\right)+3{\text{H}}_2\text{O(l})$

We now have a balanced equation, with $2$ carbon atoms on both sides, $6$ hydrogen atoms on both sides, and $7$ oxygen atoms on both sides.