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    Research and record the data book value for standard enthalpy of combustion of methane. How would your answer to (a) compare to the data book value for standard enthalpy of combusion of methane. Explain your answer? THATS THE QUESTION.

    The question above is only a 2 marker, but im unsure whether the difference is only due to errors? or is there a further chemical explanation?

    My value i worked out from the average bond enthalpies for methane was +1648
    The value i recorded and researched for methane was -890
    Whats your take on it?
    Thanks!
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    Your first answer is incorrect. The enthalpy change of combustion of methane is negative.
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    (Original post by morgan8002)
    Your first answer is incorrect. The enthalpy change of combustion of methane is negative.
    hahah yeah sorry mate my mistake..i gave only the bond enthalpies of methane...my calculated enthalpy of combustion for methane is -2182
    Now back the the first question?
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    (Original post by tariktarkan1907)

    Research and record the data book value for standard enthalpy of combustion of methane.

    Compare to the data book value for standard enthalpy of combusion of methane.
    This question makes absolutely no sense ...

    .. they are the same thing!
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    (Original post by charco)
    This question makes absolutely no sense ...

    .. they are the same thing!
    It took me a while to get it too. The question is to compare a calculated value with the standard value.
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    (Original post by tariktarkan1907)
    hahah yeah sorry mate my mistake..i gave only the bond enthalpies of methane...my calculated enthalpy of combustion for methane is -2182
    Now back the the first question?
    The answer is that they are only average bond enthalpies. The different bonds of the same type eg. C-H will have slightly different enthalpies on different molecules/different parts of the same molecule.
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    (Original post by morgan8002)
    The answer is that they are only average bond enthalpies. The different bonds of the same type eg. C-H will have slightly different enthalpies on different molecules/different parts of the same molecule.
    ahhhh now i get it. Thanks mate youve been a great help
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    (Original post by tariktarkan1907)
    ahhhh now i get it. Thanks mate youve been a great help
    You're welcome.
 
 
 
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