Step 1. Write the chemical equation for the reaction
#M_text(r): color(white)(mm)256.52color(white)(m)87.91#
#color(white)(mm)"8Fe" + "S"_8 → "8FeS"#
Step 2. Calculate the moles of #"S"_8#
#"Moles of S"_8 = 16 color(red)(cancel(color(black)("g S"_8))) × "1 mol S"_8/(256.52 color(red)(cancel(color(black)("g S"_8)))) = "0.0624 mol S"_8#
Step 3. Calculate the moles of #"FeS"#
#"Moles of FeS" = 0.0624 color(red)(cancel(color(black)("mol S"_8))) × "8 mol FeS"/(1 color(red)(cancel(color(black)("mol S"_8)))) = "0.500 mol FeS"#
Step 4, Calculate the mass of #"FeS"#
#"Mass of FeS" = 0.500 color(red)(cancel(color(black)("mol FeS"))) × "87.91 g FeS"/(1 color(red)(cancel(color(black)("mol FeS")))) = "44 g FeS"#
