Divide this problem in to two steps: 1. Convert millimoles to moles. 2. Convert moles to grams.
1.
2.65 mlmol x 1mol/1000mlmol=.00265mol
2.
.00265mol x 32.065g/1 mol=.0850g S
Let me know if you need more explanation on why I used the conversions that I did.