Empirical versus Fundamental Rate Laws

Any mathematical function that adequately represents experimental rate data can be used in the rate law. Such a rate law is called an empirical orphenomenologicd rate law. In a broader sense, a rate law may be constructed based, in addition, on concepts of reaction mechanism, that is, on how reaction is inferred to take place at the molecular level (Chapter 7). Such a rate law is called a fundamental rate law. It may be more correct in functional form, and hence more useful for achieving process improvements. 

Furthermore, extrapolations of the rate law outside the range of conditions used to generate it can be made with more confidence, if it is based on mechanistic considerations. We are not yet in a position to consider fundamental rate laws, and in this chapter we focus on empirical rate laws given by equation 4.1-3. 

---