I investigated the Arrhenius equation using the reaction between potassium iodate (containing the IO3- iodate ion) and sodium bisulfite (containing the HSO3- hydrogen sulfite ion. The ionic equations for the reaction’s two stages are as follows:

IO3- (aq) + 3HSO3- (aq) -----> I- (aq) + 3SO42- (aq) + 3H+ (aq)

5 I- (aq) + 6H+ (aq) + IO3- (aq) -----> 3I2 (aq) + 3H2O (l)

I rearranged the Arrhenius equation to give: ln(k)=(-Ea)/R)(1/T) + ln(A)

I changed the temperature of the reaction and timed the speed of the reaction, which I used to calculate the values of k. I then graphed the relation between ln(k) and 1/T , with the slope giving –Ea/R.

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My graph ended up having a slope of -0.0003, so I obtained an activation energy of 0.00024942 J/mol.

I was wondering if anyone had a theoretical value of the activation energy of this reaction I can compare my experimental value to?

  • 1
    $\begingroup$ You need to plot the other way round - lnK on y axis... $\endgroup$
    – Mithoron
    Mar 23, 2016 at 21:40
  • 1
    $\begingroup$ Thank you, I got the much more reasonable 31200 J/mol this time. $\endgroup$ Mar 25, 2016 at 1:45


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