Reaction Pathways - the various directions that a chemical reaction can take place.
Higher temperatures tend to make reaction proceed more quickly.
Catalyst - substances that increase the rate of a chemical reaction without being changed themselves. Catalysts lower the activation energy of a chemical reaction making it proceed more quickly. All chemical reactions are reversible. Some reactions will go to completion. The conversion of such a large quantity of reactants to products that what is unconverted is not noticeable and is unimportant.