Limiting Reactant and Excess Reactant

limiting reactant

the reactant that limits the amount of the other reactant that can combine and also the amount of produce that can form in a chemcial reaction

excess reactant

the reactant that is not used up completely in a chemical reaction

These problems require one addition component

• each reactant quantity must be in moles (requires a conversion if given in grams)

• use the mole ratio from the balanced equation to determine which reactant would be used entirely (just like you determine the proportion of ingredients in a recipe)

Steps to find limiting and excess

• start with a balanced chemical reaction

• Convert reactants to moles (use molar mass)

• determine limiting reactants. Convert to moles of product & use moles to mole ratio)

• calculate mass in g of product using limiting reactant (molar mass)

• figure out how much of excess reactant you have left (use limiting reactant/convert to grams of other reactant