Excess and limiting reactants

The exact amount of the reactants can be determined by the stoichiometry of the reaction. In many cases one or more reactants is supplied in excess to complete the reaction. Reactant present in the smallest stoichiometric amount is called the limiting reactant. Reactants supplied in excess of the limiting reactant are called excess reactants.
 
Oxidation- Reduction Reactions.

Oxidation: Loss of electrons from an atom
Reduction: Gain of electrons by an atom
Oxidation and reduction always occurs simultaneously so that electrons are conserved.
Cementation reaction  
 
Conclusion

In this lecture basics of stoichiometry are discussed. The concepts are illustrated with suitable examples. The reader may solve more problems to develop skills in stoichiometric calculations. Some problems are discussed in lecture 5.

References

1. R. Schuhmann, JR. Metallurgical engineering, volume 1
2. Geiger: energy balance in metallurgical processes