james_gills - 12-3-2004 at 11:23
hi all . .
need bit of help if is possible.
i am trying to calculate the activation energy of the MnO2 catalysed decomposition of H202. i realise that to do this i must plot the arrhenius plot,
of ln k vs 1/temp and take the gradient ladeda! however the problem i have is obtaining my value for K. in order to do this do i take the value from
rate = k[mn02] [h202].do i simply stick the concentrations in for each "reactant" (although mno2 isnt a reactant i know) and the overall
rate thus taking out k. is this done at every temperature?
secondly what is your advice on calculating the concentration of mno2. the problem is that i have mixed 0.1g with various amounts of h20
(2cm3,4cm3,6cm3,8cm3,10cm3) My problem is that as the catalyst forms,as im sure you will know a suspension not a solution, do i go about it by ..
(rfm/mass) * 100. is that correct?
and thirdly if i have a graph of mn02 conc against rate, which shows an initial first orer reaction, developing to a zero order one. how do i reflect
this in the rate equation, and work out the overall order of reaction? i have already discovered that the order of rection w.r.t h202 is 1st order.
any help on any of these would be brilliant! thanks in advance, james
a further problem i have now encountered is working out the coincentration of my h202 that i sued. i know it was 20 vol, but how do i convert this to
a concentration usable in the rate equations?
[Edited on 12-3-2004 by james_gills]
[Edited on 12-3-2004 by james_gills]