Practical investigations
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I am currently doing an investigation into the kinetics of the reaction between ethanedioate and manganate(VII) ions with sulphuric acid. I have tried to find the rate equation for this reaction in a number of sources but have thus far been remarkably unsuccessful in this quest. Do you know of any sources I could try, or better still know the rate equation?
Ulex replies
I have a great deal of sympathy with you here!
Those who write about this reaction seem completely ‘hung up’ about the fact of autocatalysis by manganese(II) ions and do not seem in the least interested in how this autocatalysis actually works. I’m afraid I don’t know the rate equation, nor can I find any reference to it in any literature available to me.
However I do have some experience of the practical investigation. From this I think it probable that the reaction is first order with respect to MnO4- (the graph of the catalysed reaction is clearly a first order graph). It seems likely that the reaction is first order with respect to the catalyst, Mn2+. (It is obviously not zero order and I cannot think of any reason why it should be second order). Beyond this I cannot go with any certainty. Ethanedioate and hydrogen ions are the other ‘ingredients’ to be considered.
Risk assessment
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updated: 01 March 2006
