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    Enthalpy formation value for octane

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    Using the heat of combustion of octane C8H18 (l) -5470.5 and heat of formation table determine the enthalpy formation value for octane.

    © BrainMass Inc. brainmass.com October 9, 2019, 6:03 pm ad1c9bdddf
    https://brainmass.com/chemistry/energetics-and-thermodynamics/enthalpy-formation-value-for-octane-76614

    Solution Preview

    First of all, let's balance the equation:

    C8H18(l) + 25/2 O2 ------> 8 CO2 + 9 H2O -5470.5 kJ

    Now, we need the other reactions that we can look up in the standard heat of formation table as you mentioned.

    C(s) + O2(g) ----> CO2(g) -394 kJ

    But to balance this with the first equation, we need to multiply it by 8. Therefore,

    8 C(s) + 8 O2(g) ...

    Solution Summary

    This solution uses the heat of combustion of octane to determine its enthalpy formation value.

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