How do you balance #CH_4 + O_2 -> CO_2 + H_2O#?
Look for imbalances. Both sides have one
We try to add some coefficients before each molecule to balance the number of atoms. We add a
And thus we follow the rigmarole for combustion of methane...
With alkanes with an ODD number of carbons, this approach gives integral coefficients. Try it out for propane and pentane. When you balance alkanes with EVEN numbers of carbons, this approach requires the use of half-integral oxygen coefficients. e.g. for ethane:
Alternatively you could double the entire equation to get rid of the half-integral coefficient:
Try this out for butane and hexane.
Because it is easier arithmetically to address the former stoichiometry, I tend to favour the half-integral coefficient. Of course we cannot have half a molecule of dioxygen, but we can certainly have