Limiting Reactants (click the title)

Usually, one reactant is used up before the other> this reactant is called the LIMITING REAGANT in other words, it stops or limits the reaction. The limiting reagant determines the amount of product produced. Assume one reactant is the limiting reactant and determine what quantity of the other is needed.



EXAMPLES:

1. What is the limiting reactant when 125g of P4 reacts with 325 g of Cl2 forming phosphorus trichloride?
   P4+6Cl2=4PCl3 (125g=p4/ 323g=6Cl2)
   
   125 g X1 mol/71 gX 4 mol/ 6 mol x 137.4g/ 1mol= 417 g PCl3
   

-- Michelle Haughian

Percent Yield

The theoretical yield of a reaction is the quantity of products expected (calculation). The amount produced in an experiment is the actual yield. To find the percent yield follow this calculation:

% yield= actual / theoretical x 100

Here is a short video to further explain:

http://www.youtube.com/watch?v=mOo3KuqM64c


Examples:

1. The production of Urea CO(NH2)2 is given by: 2NH3 + CO2 ---> CO(NH2)2 + H2O
If 47.7g of Urea are produced, determine

a.) theoretical yield if 1mol of CO2 reacts
1mol CO2 x 1 CO( NH2)2 \ 1 CO2 x 60.1 g= 60.1 g

b.) actual yield
47.7 g

c.) percent yield
47.7g / 60.1 g x 100= 80%

-- Krizia Umali