Kinetics—A Superficial and Thoroughly Incomplete Review

Kinetics is obviously important in polymer science, not just in the study of things like 

enough of this dalliance in other fields, let s get back to Ostwald and the order of a reaction. We ve illustrated a first-order decay process, but if we were talking about a chemical reaction, rather than radioactive decay, we would use concentration in moles per liter (mol I/1) rather than using the number of molecules or moles of a material in our differential equation. This is usually indicated by putting square brackets around the symbol for the reacting group, where k is now called the rate constant (Equation 4-3). 

Keep in mind what we ve said before, if we are describing a species (reactant) that is decreasing with time we put in a minus sign. So far so good. It should now be obvious that if the rate of the reaction depends on the square of the concentration of A (Equation 4-4), then we have what we call a second-order reaction. 

what if we now have a reaction where A and B produce products (Equation 4-5), what is the order of this reaction  

It s first-order in both A and B, but the overall order of the reaction is defined as the sum of the order of all the components, so 

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