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    the question is:
    calculate the C≡C bond enthalpy in the gas propyne using the bond enthalpy values in the table ( table gives all relevant bond enthalpies) and the enthalpy changes for the reactions below.
    C (s) ----> C (g) ∆H=715 kJ/mol
    CH3C≡CH (g) ∆fH=185 kJ/mol

    Am i right in saying i need to write out the equation of the combustion of propyne, if so what is the equation of C (s) ----> C (g) needed for
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    (Original post by FinnManley)
    the question is:
    calculate the C≡C bond enthalpy in the gas propyne using the bond enthalpy values in the table ( table gives all relevant bond enthalpies) and the enthalpy changes for the reactions below.
    C (s) ----> C (g) ∆H=715 kJ/mol
    CH3C≡CH (g) ∆fH=185 kJ/mol

    Am i right in saying i need to write out the equation of the combustion of propyne, if so what is the equation of C (s) ----> C (g) needed for
    Bond enthalpies are only valid for gaseous components.
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    (Original post by charco)
    Bond enthalpies are only valid for gaseous components.
    yes but how is this equation relevant C (s) ----> C (g) if C3H4+4O2--> 3CO2+2H2O where does the carbon by itself come in
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    (Original post by FinnManley)
    yes but how is this equation relevant C (s) ----> C (g) if C3H4+4O2--> 3CO2+2H2O where does the carbon by itself come in
    You are told to use bond enthalpy values to work out the enthalpy change of the equation.

    Bonds broken are endothermic and bonds formed are exothermic.

    So to use the bond enthalpy for CO2 you need to consider this equation:

    C(g) + 2O(g) --> O=C=O
 
 
 
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