Chemical Forums
Chemistry Forums for Students => Organic Chemistry Forum => Topic started by: AoisPokemaster on January 28, 2022, 06:55:04 AM
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Dear All,
Thanks to the help from a of of kind members of this forum, I have made a lot of progress in my academic studies as well as learning more about chemistry.
I've been writing a report on the enthalpies of combustion of different alcohols, n-alkanes, 1-alkenes, and also nitroalkanes.
Attached is the data that is collected from different thermochemical databases which take data from experiments using static bomb calorimetry, averaged with standard deviations calculated between the different values from the different databases(ignoring the error provided by them), and I also did theoretical calculations on the enthalpy of combustion, using average bond enthalpies provided by 3 sources, all aggregated as well. It is found out that for all of the values, the experimental results from the static bomb calorimetry ended up more exothermic than the calculated values. This is a problem because normally we would expect calorimetry to be less exothermic due to the incomplete heat transfer, incomplete combustion, dissipation of heat to the surroundings, etc. , and thus for the experimental results to be less exothermic than that of the calculated results.
I have been thinking about this on my own for the past 5 hours and I still couldn't think of a way to explain these results and findings. Is there any possible explanation for such occurrences? I refuse to believe that this is due to some random error, as it has occured so consistently for each of the datapoints, and they deviate by such a significant amount(more significant than both the standard deviation and the error of the experimental datapoints)