[linyen416]

In the iodine clock reaction involving persulfate and potassium iodide: why is the experimental method of determining rate law called 'method of initial rates' when acutally the 'average' rate is measured? How does 'intial' come into play?


Also, is this calculation correct:
rate = (volume of thiosulfate added* concentration of thiosulfate added)
            (2*total volume of reaction mixture*time for blue colour)


Regarding rection mechanism, is the reaction mechanism of this iodine clock just simply the three equations? The first being KI reacting with persulfate
 Second: iodide reacting with thiosulfate
third: iodine freed from first reaction now reacting with starch indicator to form blue complex?


Or is the reaction mechanism harder to determine?

[linyen416]

Also, the overall rate law is determined by the slowest step in the reaction ‘mechanism’ – the step by step sequence of elementary reactions by which overall chemical change occurs.\

Then would I be right to say that the slowest step = rate determining step = first step = reaction between persulfate and KI?