Gravimetric - Calculation question

[Christiano]

Okay so I'm asked to find the % mass of sulfur present in the form of sulfate ions. I'm given the mass of BaSO4, so when you calculate the mol of BaSO4 then work out the stoich mol of sulfur, when calculating the mass of sulfur atoms, do you use sulfurs molar mass or the molar mass of SO4?

I'm a bit confused because the 2 chemistry teachers at my school are contradicting each other on using sulfur's molar mass or SO4 molar mass to work out the mass of sulfur atoms and hence the % of sulfur atoms.

[scocliffe09]

Okay so I'm asked to find the % mass of sulfur present in the form of sulfate ions. I'm given the mass of BaSO4, so when you calculate the mol of BaSO4 then work out the stoich mol of sulfur, when calculating the mass of sulfur atoms, do you use sulfurs molar mass or the molar mass of SO4?

I'm a bit confused because the 2 chemistry teachers at my school are contradicting each other on using sulfur's molar mass or SO4 molar mass to work out the mass of sulfur atoms and hence the % of sulfur atoms.

Use sulfur's molar mass as you're trying to find the percentage mass of sulfur atoms.
The only reason sulfate is mentioned in the title is because the sulfur atoms are present as sulfate molecules.