2Always start with the balanced equation N2(g) + 3H2(g) → 2NH3(g)The mole ratio is 1:3:2If we have 1 mole of N2 and 6 moles of H2 what is the limiting reagent?What is the excess reagent?
3Excess reagent – the reactant that is present in more that he required amount for a complete reactionLimiting reagent – the reactant that is completely consumed in a chemical reaction
4To solve these problems use the mole bridge Remember:Only moles can crossSpecifically only the original mole can crossAnd to cross you need to multiply or divide
5You need a 1:1 comparison to decide who crosses! 0.75 mol of Iron react with 0.6 mol of oxygen to form iron(III)oxide.How many moles of iron(III)oxide form?4Fe O → Fe2O30.75 mol0.60 molX molYou need a 1:1 comparison to decide who crosses!