A2 Chemistry
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I'm cuurently studying the reaction between Iodine, propanone and acid. When I tried to find the order of reaction with respect to Iodine, using titration (quenching with NAHCO3 and titrating with NAS2O3), something else seems to be happening:
When i plot Rate against Concentration, it is a dead straight line, but at higher concentrations it seems to be going into 1st or 2nd order. I've been pondering and I've boiled it down to either the auto catalst or the ionine (I3-) complex.
Please help me out!
Corrie writes ...
I'm not sure what you mean by 'higher concentrations' here? Do you mean 'longer times' or have you been doing experiments starting with different concentrations of iodine, propanaone etc?
Come back to us via Re:act, not via email. please.
Reasons for deviations form the zero order behaviour with respect to iodine as the reaction progresses could be due to the fact that the propanone concentration is decreasing significantly and the assumption that it is 'constant' is no longer valid.
I doubt that the effect you are seeing is due to autocatalysis by the acid (HI) formed as the H+ concentration is already high due to the presence of the sulphuric acid.
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updated: 01 October 2007
