kJ vs. kJ per mole?

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Joshua Beristain 2J
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kJ vs. kJ per mole?

Postby Joshua Beristain 2J » Tue Jan 17, 2017 5:34 pm

I have currently worked through problems 8.57, 8.59, 8.61, and 8.63 (part a), and they all seem like they are asking for the same thing- the standard reaction enthalpy. However, I don't understand then why the answer in 8.57 and 8.59 is in kJ per mole and the answer for 8.61 and 8.63 (just looking at part a) is in kJ. Could someone please explain?

Monica Habashy 3A
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Re: kJ vs. kJ per mole?

Postby Monica Habashy 3A » Tue Jan 17, 2017 8:48 pm

You use KJ per mole when you're finding the standard enthalpy of formation because it is the formation of 1 mol of a compound from its constituent elements. However, if you're just finding the enthalpy of a reaction you just use KJ. Also, my TA said that bond enthalpies can be written in KJ or KJ per mole.

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Re: kJ vs. kJ per mole?

Postby stephanieyang_3F » Wed Jan 18, 2017 1:02 am

In problem 8.57, they asked for the reaction enthalpy for that particular reaction. If the given enthalpy of combustion values are in kJ/mol already, do we assume that the reaction enthalpy in the answer also be kJ/mol? Cause usually reaction enthalpy is in kJ and that's what I would've put if the given values didn't have the kJ/mol units so I was confused as well...

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