Author Topic: Chemistry enthalpy question  (Read 835 times)

Offline ayesha.

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Chemistry enthalpy question
« on: May 28, 2010, 02:46:51 pm »
Calculate the standard enthalpy change for the following rxn.

CH4 + 2O2(g) ? CO2(g) + 2H2O(l)

?Hf CO2 = -394 KJ/mol
?Hf H2O = -286KJ/mol
?Hf CH4 = -75 KJ/mol

Using the standard enthalpy of formation of methane and the data given below calculate the mean bond enthalpy of C-H bond in methane.

C(s) ? C(g) ?Hat of graphite = +715 KJ/mol
H2(g) ? 2H(g) ?H= +436 KJ/mol


Using the C-H bond enthalpy calculated and the standard enthalpy change for the reaction given below, calculate the mean bond enthalpy of the C-C bond in propane

C3H8 (g) ? 3C(g) + 8H(g)

Offline ayesha.

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Re: Chemistry enthalpy question
« Reply #1 on: May 28, 2010, 02:48:56 pm »
enthalpy change for the last rxn is +4020 KJ/mol

nid404

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Re: Chemistry enthalpy question
« Reply #2 on: May 28, 2010, 02:55:23 pm »
What's the "?"  ?

Offline ayesha.

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Re: Chemistry enthalpy question
« Reply #3 on: May 28, 2010, 08:59:16 pm »
delta

Offline unknown 101

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Re: Chemistry enthalpy question
« Reply #4 on: May 28, 2010, 09:03:54 pm »
which pastpaper is this question from??
cuz if its not from a past paper then upload it here, cuz ur confusing everybody!!

Offline ayesha.

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Re: Chemistry enthalpy question
« Reply #5 on: May 29, 2010, 08:31:41 am »
its not a pastpaer question
nvm i got the answer