Hc and Hf

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Blake_Katsev_2E
Posts: 113
Joined: Wed Sep 21, 2016 2:57 pm

Hc and Hf

Postby Blake_Katsev_2E » Mon Jan 16, 2017 1:24 pm

When would you use Hc and when would you use Hf?

Michael Sparks 2F
Posts: 20
Joined: Fri Jul 22, 2016 3:00 am

Re: Hc and Hf

Postby Michael Sparks 2F » Mon Jan 16, 2017 4:04 pm

Hf would be used in situations concerning the energy gained or lost as bonds are formed or broken during a chemical reaction.

Shelby Slaughter 3D
Posts: 24
Joined: Fri Jul 15, 2016 3:00 am

Re: Hc and Hf

Postby Shelby Slaughter 3D » Mon Jan 16, 2017 4:08 pm

Hf is for standard enthalpy of formation which is the standard reaction enthalpy for forming one mole of a substance from its elements, but only when its elements are in their most stable form. Where have you seen Hc??

Shelby Slaughter 3D
Posts: 24
Joined: Fri Jul 15, 2016 3:00 am

Re: Hc and Hf

Postby Shelby Slaughter 3D » Mon Jan 16, 2017 10:59 pm

I believe that Hc is the standard enthalpy of combustion, or the enthalpy change per mole of something burned during combustion. So, I would say it is used for combustion reactions. However, I am unsure if reactants and products must be in standard state. The text book only say "under standard conditions". See textbook page 291


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