Answer
$0.206$ $mol$ $HCl$
Work Step by Step
Determine the limiting reactant. Choose one of the reactants and determine how much we need compared to how much is available. We choose to compare HCl.
$0.652 mols$ $HCl (avaliable)$
$0.223 mols$ $FeS$$\times\frac{2 mol HCl}{1 mol FeS}$$=0.446$ $mols$ $HCl (needed)$
The moles of excess reactant is found by subtracting the needed amount from the available amount.
Excess amount of $HCl$
= $avaliable - needed$
=$0.652$ $mols$ - $0.446$ $mols$ $HCl$
=$0.206$ $mols$ $HCl$
