Limiting/Excess Reactants, Fractional Conversion and Extent of Reaction

The reactant that would run out before the reaction proceeded to completion is called the limiting reactant, and the other reactants are termed excess reactants.

The fractional excess of the reactant is the ratio of the excess to the stoichiometric requirements.

Fractional excess of A =[ (moles A)feed – (moles A)stoich]/(moles A)stoich

The extent of reaction is a quantity used to determine how much a reactant reacted.

Fractional conversion = moles reacted/moles fed

For tutorials visit:

http://www.chemcollective.org/activities/tutorials/stoich/reaction_stoi

http://chemistry.about.com/od/stoichiometry/