Reaction
SiCl₄+ 2Mg ⇒ Si + 2MgCl₂
to find limiting reagents: divide the number of moles by their coefficients
SiCl₄ = 1 mole : 1 (coefficient) = 1
Mg = 5 mole : 2 (coefficient) = 2.5
SiCl₄ as a limiting reactant (smaller), and Mg as an excess
then all the compounds involved in the reaction are based on moles of SiCl₄
Si produced =
[tex]\tt \dfrac{coefficient~Si}{coefficient~SiCl_4}\times mole~Si=\dfrac{1}{1}\times 1=1[/tex]
Reacted Mg (excess) = 2/1 x 1 = 2 mole
mole Mg remaining = 5 - 2 = 3 mole