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Topic: heat and enthalpy  (Read 2859 times)

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Offline u0625552

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heat and enthalpy
« on: October 14, 2009, 05:52:48 PM »
The standard enthalpy of formation of n-octane is -249.95 kJ/mol. Compute the amount of heat liberated when 3.49 g of n-octane is burned completely with excess oxygen to form carbon dioxide and liquid water.

How would I solve this problem? I don't know where to start.
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Offline Darwin

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Re: heat and enthalpy
« Reply #1 on: October 14, 2009, 05:57:06 PM »
When the standard enthalpy of formation is -249.95 kJ/mol, it means that 249.95 kJ is liberated per mole substance in the combustion reaction. So convert the grams of n-octane into moles.
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Offline u0625552

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Re: heat and enthalpy
« Reply #2 on: October 19, 2009, 03:37:51 PM »
I converted the grams to mole and got .0306. Then i multiplied the -249.95 and got -7.6... But that is not the right answer. What do i do from there?
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