Help with Stoich limiting reactant Lab urgent!! 1. I need to find the mass of the excess reactant. This was a lab i did. so its BaCl2.2H20 + Na2So4 --> BaSO4 + 2NaCL. The data i have calculated thus far is. moles of BaSO4=0.0019 mol moles of BaCl2=0.0019 mol moles of Na2SO4=0.0019 mol mass of BaSo4=.4524g mass of BaCl2=.4641g mass of Na2So4= .2698g Mass of entire salt mixture=1.0038g The limiting reactant is SO4 and excess is Ba. BaSo4 is the precipitate. How do i get the excess reactant!!!