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-   -   some probem in my salters investigation (http://www.physicsforums.com/showthread.php?t=274660)

i25959341 Nov24-08 03:30 PM

some probem in my salters investigation
 
i m doing the kinetic of iodine and propanone in acid condition using colorimeter and observing the absorbance and initially i dont think i will need a calibration curve becos absorbance is poprptional to concentration and i only need to look the shape of the graph to determine the order of the reaction, hence i plot an graph with absrobance against time and find the Initial rate for each concentrations of the reactnats and plot a graph wiht rates agasint concentration.


now the problem is i also wanna know the activation energy and need to plot the arrhenius plot lnk =lna-lnE/PT.
now i wanna save time, so i use the absorbance against time graph to find the initial rate of the reaction and use the rate law ,rate=k[r]^e[g]^f,(at this point of the experiment i expected that i kno the order of the reaction alreayd) and basiclly find k

and i just wanna ask, since absorbance is proportional to concentration , thus will the tangent at time zero at absorbance against time graph be the initial rate value for my experiment or is it missing a constant??

secondly is my method of determining activation energy experiment sound correct??


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