Limiting Reactant u The limiting reactant is the reactant you run out of first. u The excess reactant is the one you have left over. u The limiting reactant determines how much product you can make
Calculating Limiting Reactant u Do two stoichiometry problems. u The one that makes the least product is the limiting reagent.
u If 10.6 g of copper reacts with 3.83 g S. How many grams of product will be formed? 2Cu + S Cu 2 S 10.6 g Cu 63.55g Cu 1 mol Cu 2 mol Cu 1 mol Cu 2 S 1 mol Cu 2 S 159.16 g Cu 2 S = 13.3 g Cu 2 S 3.83 g S 32.06g S 1 mol S 1 S 1 Cu 2 S 1 mol Cu 2 S 159.16 g Cu 2 S = 19.0 g Cu 2 S = 13.3 g Cu 2 S Cu is Limiting Reagent
Your turn Mg + 2HCl MgCl 2 + H 2 u If 10.1 g of magnesium and 2.87 g of HCl gas are reacted, how many grams of hydrogen gas will be produced? u What is the excess reactant?
Your Turn II 2Al + 3CuSO 4 Al 2 (SO 4 ) 3 + 3Cu u If 10.3 g of aluminum are reacted with 51.7 g of CuSO 4 how much copper will be produced? u What is the excess reagent?