LIMITING REACTANTS

-In chemical reactions,usually one chemical gets used up before the other.
     -The chemical used up first is called the limiting reactant
     -Once it is used up the reaction stops
     -L.R determines the quantity of products formed
-To find the L.R assume one reactant is used up

EXAMPLE
Determine the L.R when 1.4mol of hydrogen reacts with 0.89 mol of oxygen
2H2 + O2 -> 2H2O

1.4mol x 1 = 0.70mol of oxygen
              2
There is 0.70mol of oxygen used up out of the 1.4mol which makes hydrogen the L.R

OR

0.89mol x 2 = 1.78mol of H2
                1

1.78mol of hyrdrogen are needed when there is only 1.4mol, which makes hydrogen the L.R

HELPFUL LINKS
http://www.chem.tamu.edu/class/majors/tutorialnotefiles/limiting.htm http://www.mikeblaber.org/oldwine/chm1045/notes/Stoich/Limiting/Stoich07.htm
http://www.youtube.com/watch?v=rESzyhPOJ7I

K.P