if 25.06 grams of magnesium react with 70.87 grams of hydrochloric acid, which one is the limiting reactiant?

Answer 1

Mg(s) + 2HCl(aq) ==> MgCl2(aq) + H2(g) ... balanced equation

moles Mg present = 25.06 g x 1 mol/24.3 g = 1.031 moles Mg

moles HCl present = 70.87 g x 1 mol/36.5 g = 1.942 moles HCl

For me the easiest way to identify the limiting reactant is to simply divide the moles of each by their respective coefficient in the balanced equation and see which is the lower amount. Thus...

For Mg: 1.031 moles/1 = 1.031

For HCl: 1.942 moles/2 = 0.9798 --> LIMITING REACTANT is HCl