The FeSOJ Complex

Formation of the FeSOJ complex is described by the elementary reaction 

In this expression = 6.37 x 10 L/mol s at 25 C. The reverse reaction rate (first-order) is given by /f = k (FeSO ). The equilibrium constant is = 205/mol, from which (because = kjk and assuming the principle of detailed balancing) we compute k = 31/s. Calculated rates and concentrations for this reaction as a function of time are given in Fig. 2.8. Note that the overall rate R in Fig. 2.8[b]) equals the difference ( + - / ). 

---

Clearly, the reaction order and form of the empirical rate law could not have been predicted from the overall reaction. If we hold P , constant, for example assuming oxidation is in a turbulent, aerated stream, then the reaction is said to be pseudo first-order. Another example of a second-order rate is formation of the FeSOJ complex (see Section 2.7.1). 

---