Procedure 4.6.b Determination of the Formation Constant

Load one of the stopped-flow syringes with Stock 1 and the other with the Reaction 1 solution from Table 4.7. 

Observe the absorbance decrease at 444 nm (the absorbance maximum for the [Fe(CN)5(H20)]3 complex) over at least three reaction half-lives. Carry out three trial runs. 

For each run, plot In Aw — At vs t, where At is the measured absorbance at time, I. Obtain the pseudo-first-order rate constant, kOBS (s-1) from the slope of the plot. 

Report the average of your three trials for each reaction 1, 2, and 3. 

To obtain the formation rate constant, kf (M-1 s 1), plot kOBS vs [AA]. 

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