Clarification

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Sabrina 1F
Posts: 7
Joined: Wed Nov 16, 2016 3:03 am

Clarification

Postby Sabrina 1F » Fri Jan 12, 2018 2:50 pm

I am a little confused about the relationship between heat transfer and enthalpy: Is Heat Transfer the transference of energy, and enthalpy is heat transfer at a constant pressure?

Grace Han 2K
Posts: 33
Joined: Tue Nov 15, 2016 3:00 am

Re: Clarification

Postby Grace Han 2K » Fri Jan 12, 2018 2:55 pm

I had a similar question and found this link helpful: https://chemistry.stackexchange.com/que ... and-heat-q

It says, "Enthalpy and heat are entirely different things.

Enthalpy is a function of state. If you know the state of a system, you know its enthalpy. If you know the starting and ending states of a process, you can find the enthalpy change.

Heat, on the other hand, is an inexact differential. Knowing the initial and final states of a process is not enough information to tell you the heat transfer. Instead, the heat transfer depends on the particular path taken between the states."

Kayla Danesh 1F
Posts: 38
Joined: Thu Jul 13, 2017 3:00 am

Re: Clarification

Postby Kayla Danesh 1F » Fri Jan 12, 2018 4:25 pm

While enthalpy is a state function, heat is not. So, you can calculate enthalpy by simply doing (final-initial). On the other hand, heat is not a state function. Heat is defined by the path it takes to get from point 1 to point 2, which is why we can't treat it like a state function.

Justin Chang 2K
Posts: 53
Joined: Fri Sep 29, 2017 7:04 am

Re: Clarification

Postby Justin Chang 2K » Sat Jan 13, 2018 10:27 pm

Yeah, for heat transfer you need to know every single individual step that is involved in the reaction. However, for enthalpy you only need to know the initial and final amounts since it is a state function; it doesn’t matter the pathway that is taken in order to reach the final amount.


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