Answer: Cu is limiting and 1.00 mole of excess S remain
Explanation:
The chemical balanced reaction is:
[tex]2Cu+S\rightarrow Cu_2S[/tex]
According to stoichiometry :
2 moles of [tex]Cu[/tex] require 1 mole of [tex]S[/tex]
Thus 10.00 moles of [tex]Cu[/tex] will require=[tex]\frac{1}{2}\times 10.00=5.00moles[/tex] of [tex]S[/tex]
Thus [tex]Cu[/tex] is the limiting reagent as it limits the formation of product and [tex]S[/tex] is the excess reagent.
Moles of S left = (6.00-5.00) moles = 1.00 mole
Thus Cu is limiting and 1.00 mole of excess S remain.