rates of reaction

... reaction. Introduction: Chemical engineers exploit chemical reactions to produce materials on a commercial scale. One of their principal activities is the design and operation of chemical reactors. In order to accomplish design goals, the engineer often needs to know the kinetics of a reaction -- the factors that influence the rate of the reaction. In what follows, a brief discussion of the basic ideas in chemical kinetics is presented along with the mathematical models used to study the kinetics of chemical reactions. The close resemblance of the mathematical equations modeling chemical kinetics to those modeling population dynamics will become apparent. Appropriate links to topics in population dynamics will be indicated for you to explore if you so desire. Reaction Rates A chemical reaction involves one or more substances (reactants) that react to produce other substances (products). As the reaction proceeds, some chemical species are depleted while others are formed. Certain laws govern this process, and these laws can be expressed in terms of mathematical equations Balance Laws One of the assumptions made in chemical kinetics is that the number of atoms is preserved, i.e. atoms are neither created nor destroyed. For example, if there are atoms of Oxygen, , present before the reaction begins, then there will be the same number, , of atoms of Oxygen during all stages of the reaction. This is illustrated by the following stoichiometric equation describing the decomposition of nitrous oxide (a gas) into nitrogen and oxygen gases (do not confuse the nitrogen and oxygen gases, and , with the elements Oxygen, , and Nitrogen, ): The following reactions take place inside certain types of automobile catalytic converters, based on the oxidation reaction of , hydrocarbons and (the purpose is to avoid pollution by carbon monoxide): Note the conservation of atoms of C, H and O. Another common reaction takes place whenever you take an ...: Suppose moles of react with moles of to produce moles of and moles of : Let , , etc. represent the molar amounts of the chemical species in the reaction (measured in kmol, for example). Recall that the derivative of a quantity with respect to time, , expresses the instantaneous rate of change of that quan ...