# When writing a formula, why do the one's drop out?

##### 1 Answer
Sep 10, 2016

Are you asking why we don't write, for instance,
$2 {H}_{2} + 1 {O}_{2} \rightarrow 2 {H}_{2} O$?

#### Explanation:

Well the $1$ is superfluous. It is understood that there is 1 equiv of dioxygen gas in the stoichiometric equation.