Testing the Arrhenius Relationship

Suppose that the rate constant for a reaction has been determined at sevo-al different temperatures, using the techniques described above. We then can determine whether the Arrhenius relationship is obeyed. If it is, the value of the activation energy can be obtained fi om the data. 

If the measured rate constants obey the Arrhenius relationship, a plot of In it against 1 /Twill be a straight line. The value of the slope will be —E/R) and the activation energy, E, can be calculated fixtm the slope. 

The compound 2,2 -azobis(isobutyroiiitrile) (AIBN) commonly is used to initiate polymerization reactions because it decomposes spontaneously into two free radicals. Each free radical then can react with a monomer to start a growing polymer chain. Not surprisingly, compounds such as AIBN are called initiators.  

The use of supercritical carbon dioxide (SCCO2) as a polymerization medium has attracted widespread attention because it can eliminate the need for organic solvents and/or eliminate the need to treat large quantities of wastewater produced in the polymerization reactor. Therefore, the decomposition of AIBN has been studied in scCOa with the following results. 

TaUe 6-5 First-Order Rate Constant (ilb) for AIBN Decomposition as a Function of Temperature 

---