Question

Elemental sulfur occurs as octatomic molecules, S8. What mass of fluorine gas is needed to react completely with 19.0g of sulfur to form sulfur hexafluoride?

Answer 1

first you need a balanced equation, so:
24F2+S8 --> 8SF6

then find the no. of moles of s8 (which is 19g divided by molar mass of s8)

then use the reaction ratio of 24:1 to multiply your answer to get number of moles of fluorine

then convert from moles to mass using m=n*M

Answer 2

19.0/256.56 multiply by 24 mol F2 multiply by 38g F2 after calculation will give you the mass in grams of F2.