# In chemical equations, what numbers often appear in front of a chemical formula?

Apr 7, 2017

$\text{The so-called stoichiometric coefficients............}$

#### Explanation:

Let's examine a combustion reaction (I choose an odd-numbered alkane so that I don't have to use half-integral coefficients):

${C}_{5} {H}_{12} + 8 {O}_{2} \rightarrow 5 C {O}_{2} + 6 {H}_{2} O$

Is this balanced? Don't trust my 'rithmetic!

The $1$ understood to be in front of the pentane, the $8$ in front of the dioxygen, the $5$ in front of the carbon dioxide, and the $6$ in front of the water, $\text{ARE THE STOICHIOMETRIC COEFFICIENTS}$ $\text{OF THE REACTANTS AND THE PRODUCTS.}$