This document discusses limiting and excess reactants in chemical reactions. It defines a limiting reactant as the reactant that is consumed first or ends the reaction. It provides two methods to determine the limiting reactant: 1) converting reactants to moles and seeing which produces the fewest moles of product, and 2) comparing reactant ratios in the chemical equation and actual amounts. The excess reactant is any reactant other than the limiting one that remains after the reaction. It defines percent excess reactant as the moles in excess divided by the moles required to react with the limiting reactant.

1. Limiting and Excess
Reactant

2. Contents
Limiting Reactant
Ways to find Limiting reactant
Excess Reactant
% Excess Reactant
% Excess Air
% Conversion

3. Limiting Reactant
The reactant which consumes earlier
or
Limiting reactant is a specie that ends the
reaction.
C17H16 + 11O2 CO2 + 8H2O

4. How to find Limiting reactant
NH3 +O2 NO +H2O
You cannot compare grams of different compounds,
so the first step is to convert the grams into
moles
1) determine which reactant will produce the
fewest moles of product

5. CHCI3 +CI CCI4 +HCI
1)First balance the equation.
2) Covert moles of CHCI3 into moles of CCI4.
3) Covert moles of CI into moles of
CCI4.(product)
4)

6. Another method to find L.R
By comparing the ratios of reactants.
3Fe + Sb2S3 2Sb +3FeS
1) First find moles of every component.
2) Find the ratio of reactants in feed
3) Ratio in chemical equation 3
1

7. To determine the mass of reactant that
reacted with other reactant
 we need to convert moles of the limiting
reactant into moles of the other reactant to
find out how much of the other reactant is
reacted.

8. Excess Reactant
The reactant other than limiting reactant.
The reactant that remains, after the reaction is
over.
C17H16 + 11O2 CO2 + 8H2O

9. % Excess Reactant
moles in excess
moles require to react with limiting reactant
enter – require
require