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By: Ping Y. Furlan, University of Pittsburgh at Titusville
Hydrocarbons and alcohols are both common fuels used for heating or running automobiles. Alcohols are reported to burn more cleanly than hydrocarbons, and ethanol is currently being used up to 10% in most gasoline [1]. The cleaner burning gasoline on the market contains both ethanol and methanol.
In this activity, you will use CAChe-ProjectLeader to predict and compare the fuel values of straight chain hydrocarbons (n-CnH2n+2) and straight chain primary alcohols (1-CnH2n+1OH), and investigate the effect of increasing the number of carbon atoms on the fuel value. Then, you will verify the reliability of your predictions using the experimental fuel values of these fuels.
The combustion processes for the hydrocarbons are represented by Equation 1:
And the combustion processes for the alcohols are represented by Equation 2:
The heats of combustion, H (kcal/mol), for both hydrocarbons and alcohols can be calculated from the heats of formation, Hf (kcal/mol), using Equation 3:
The fuel value, H (kcal/g), is determined by dividing the heat of combustion, H (kcal/mol), by the molar mass (g/mol) of the fuel using Equation 4:
The negative sign of the fuel value indicates the exothermic nature of the reaction. The more negative the value is, the more energy is released per gram of the fuel, and the "higher" the fuel value is.
Acknowledgement:
Special thanks go to Dr. Lisa Bell-Loncella for her insightful suggestions and helpful discussions.
References:
Special thanks go to Dr. Lisa Bell-Loncella for her insightful suggestions and helpful discussions.
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