How would you balance: S8 + O2 --> SO3?
Stoichiometrically...garbage in equals garbage out....
To make this a little easier we could use fractional coefficients...
Industrially, this is performed by the
And then this is further oxidized to
This must be a very dirty, nasty, and smelly process. It is undoubtedly necessary to perform this reaction to produce an industrial feedstock.