# What is the whole number that appears before a formula in an equation?

Mar 2, 2017

Do you mean the $\text{stoichiometric coefficients}$?

#### Explanation:

Let's take hydrocarbon combustion, that of pentane, which we could represent as:

${C}_{5} {H}_{12} \left(l\right) + 8 {O}_{2} \left(g\right) \rightarrow 5 C {O}_{2} \left(g\right) + 6 {H}_{2} O \left(l\right)$

The numbers: $1 , 8 , 5 ,$ and $6$ are the stoichiometric coefficients of $\text{pentane, dioxygen, carbon dioxide, and water}$ in the stoichiometrically balanced equation.

For even numbered alkanes, we could use non-integral stoichiometric coefficients:

${C}_{6} {H}_{14} \left(l\right) + \frac{19}{2} {O}_{2} \left(g\right) \rightarrow 6 C {O}_{2} \left(g\right) + 7 {H}_{2} O \left(l\right)$

Is this equation stoichiometrically balanced? Don't trust my arithmetic!