If we know that:
$1g$ of carbon + $1.33g$ of oxygen = carbon monoxide
$1g$ of carbon + $2.66g$ of oxygen = carbon dioxide
My question is: why is that in the second case where we doubled the amount of oxygen we don't get double the amount of the first case (2 times carbon monoxide)
Or why don't we get the same amount of carbon monoxide and the remaining mass of the products is simply oxygen that didn't form any bonds.
Basically, what forces the reaction to occur in a certain way just because the proportions are different but the elements are the same.