A student after doing an experiment on chemical kinetics, decided that the rate law of the reaction is $u = k[\ce{IO3-}]$ which is correct, but do the data below match with this? Or does he have to repeat the experiments? $$\ce{IO3- + 8I- + 6H+ → 3I3- + 3H2O}$$

In order to decide the rate law he took into consideration the data below:

  1. experiment: $\pu{1 mL}~\ce{IO3-}$; time: $\pu{11 min}$
  2. experiment: $\pu{0.75 mL}~\ce{IO3-}$; time: $\pu{8 min}$
  3. experiment: $\pu{0.5 mL}~\ce{IO3-}$; time : $\pu{5.7 min}$

Looking at the rate law, the order is supposed to be one. I know that in order to conclude if the data matches the rate law I have to find out if the concentration is linear combination of time. But I'm confused, because I don't know anything about the concentration and thinking about it I guess I should at least talk about relative concentration? But still I don't know how.

  • 1
    $\begingroup$ I have no clear idea what you mean by $x~\pu{ml}$ of $\ce{IO3-}$. The equation indicates that the reaction is a system of elementary reaction steps. It is very rare to have 3 body collisions. 4 or more can be safely ignored in almost all chemical contexts. Your equation has 15 reactants and 6 products, hence is not a elementary reaction. It is actually a very well known reaction, especially in introductory chemical kinetics classes, the Dushman reaction. [...] $\endgroup$
    – alphonse
    Sep 26, 2017 at 17:19
  • $\begingroup$ [...] (cont. alphonse) Without any other information, I'd assume that the volumes (ml) were amounts used to titrate a given (constant) amount of the reaction, thus they are measures of concentration. $\endgroup$ Sep 27, 2017 at 10:11


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