kj/mol vs kj

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Hannah Chew 2A
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kj/mol vs kj

Postby Hannah Chew 2A » Mon Jan 22, 2018 4:58 pm

Hi, I’m very confused about when we should use kj/mol and when we should use kj. The solution manual gives different units for each type of problem, some of them even contradicting each other. Can anyone give me a concrete answer when to use what? Here are a few examples of where I am confused.

1. In #65, it asks us for the standard enthalpy of formation, which the book stressed kj/mol, but then the solution manual gave the answer in kj?
2. In #57 and #73 it asks us for reaction enthalpy and answer is kj/mol, but in #55 when it asks the same thing, the answer is kj.

Any help is appreciated:)

Tiffany Cao 1D
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Joined: Fri Sep 29, 2017 7:03 am
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Re: kj/mol vs kj

Postby Tiffany Cao 1D » Mon Jan 22, 2018 5:21 pm

Since enthalpy is essentially heat (which is measured in kJ), it doesn't really matter if you use kJ/mol or kJ for enthalpy.

Evelyn L 1H
Posts: 67
Joined: Fri Sep 29, 2017 7:05 am

Re: kj/mol vs kj

Postby Evelyn L 1H » Wed Jan 24, 2018 12:12 am

The kJ/mol describes the enthalpy of formation of a mole of a molecule (like H2O) but when you get the enthalpy of formation for the entire reaction, it's not per mole because it's for the whole reaction. (I think)

Return to “Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)”

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