J.R. S. answered • 09/21/20

Ph.D. in Biochemistry--University Professor--Chemistry Tutor

It wouldn't give you a different answer if you did it correctly. We always assume 100 g because the definition of PERCENT is parts per 100, not parts per 200 or parts per 700. *It just makes our calculations much easier.*

If we had, let's say, 23% C (carbon).

If we assume 100 grams of substance, we would have 23 g of C, or 0.23 g of C per g of substance

If we assume 200 grams of substance, we would have 46 g of C, or 0.23 g of C per g of substance.

No difference on a per gram of substance basis.