# When balancing a chemical equation, can you adjust the number that is subscripted to a substance formula?

Mar 4, 2017

$\text{Usually no, in that the subscripts relate to a particular formula......}$

#### Explanation:

Consider the combustion of alkanes, methane for a start:

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

The stoichiometric coefficients (from the left the $1$, the $2$, the $1$, the $2$) MAY BE adjusted, i.e. simply by using say $32 \cdot g$ of methane; of course the mass of dioxygen must be increased proportionately.

The subscripts, that which represents the number of atoms in a molecule, are FIXED, because these represent actual molecules, actual chemical species.