Determining The Enthalpy Of Combustion Of Kerosens.

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Below, one representative graph and a set of sample calculations are included which will show how the values for the enthalpy of combustion of the fuel sources are deduced.

Graph 1: Scatter plot showing the change in the temperature of 80.0mL of distilled water in the tin calorimeter during and after the combustion of the kerosene for the first conducted trial.

The linear trendline was created for the last three data points, where the water was allowed to cool, which was then extrapolated backwards to account for the total decrease in the temperature of the water due to a loss of heat energy to the surrounding environment. The difference between the highest and lowest temperature values will then be used to calculate the total change in
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Sample calculation 4: Determining the enthalpy of combustion of kerosene for the first trial.

=

, given that the main hydrocarbon in kerosene is C12H26 (CRCT 2011)

Sample calculation 5: Averaging the values for the enthalpy of combustion of kerosene for the three trials, to reduce random error.

Since there are no actual scientific resources stating the enthalpy of combustion for these exact chemical substances, there can be a comparison made instead to the theoretical standard enthalpy of combustions of the main hydrocarbons and combustible organic substances present in each fuel.

Sample calculation 6: Determining the standard enthalpy of combustion of the main hydrocarbon in kerosene through the use of bond dissociation enthalpies.

C12H26 + 18.5 O2(g) → 13 H2O(l) + 12 CO2(g)

Sample calculation 7: Determining the percentage error of the experimental enthalpy of combustion of kerosene, when compared to the calculated theoretical standard enthalpy of
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This could be caused by the evaporation of water which allows water to escape the system in the form of steam. With less water being present in the tin calorimeter, less energy is required to increase the temperature of water, resulting in larger differences between the final and initial temperatures of the water. This error has a greater effect on the fuel sources that managed to raise the water’s temperature close to the boiling point, resulting in relatively higher enthalpies of

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