\(4C + S_8 \rightarrow 4CS_2\)
\(\therefore \) Number of moles of carbon = \(\frac 4{12} = 0.33 \,mol\)
Number of moles of sulphur = \(\frac 8{256.8} = 0.031\, mol\)
\(\because \) 1 mole of S8 react with = 4 mole of carbon
\(\therefore \) \(\)0.031 mole of S8 react with = (4 x 0.031) mole of carbon
= 0.12 mol of carbon
but we have 0.33 moles of carbon
\(\therefore \) S8 is a limiting reagent.
\(\therefore \) Number of moles of CS2 formed = 0.031 x 4
\(\therefore \) Weight of CS2 = 0.031 x 4 x 76 = 9.42 g
Number of moles of carbon left = 0.33 - 0.12 = 0.21 mol
or
= 0.21 x 12 g
= 2.52 g
Hence, 9.42 g CS2 will formed and 2.52 g carbon left unreacted.