First we need to calculate the number of moles of FeS[tex]_{2}[/tex]:
number of moles = mass (grams) / molecular mass (g/mol)
number of moles of FeS[tex]_{2}[/tex] = 198.2/120 = 1.65 moles
From the chemical reaction we deduce that:
if 4 moles of FeS[tex]_{2}[/tex] produces 8 moles of SO[tex]_{2}[/tex]
then 1.65 moles of FeS[tex]_{2}[/tex] produces X moles of SO[tex]_{2}[/tex]
X = (1.65×8)/4 = 3.3 moles of SO[tex]_{2}[/tex]
Now we can calculate the mass of SO[tex]_{2}[/tex]:
mass (grams) = number of moles × molecular mass (grams/mole)
mass of SO[tex]_{2}[/tex] = 3.3×64 = 211.2 g