Phase Changes

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Vuong_2F
Posts: 90
Joined: Sat Sep 14, 2019 12:17 am

Phase Changes

Postby Vuong_2F » Sun Jan 26, 2020 8:01 pm

For reactions where substances are not in their most stable/standard phase, how would you account for that when calculating enthalpies?

Christine Honda 2I
Posts: 116
Joined: Sat Sep 14, 2019 12:17 am

Re: Phase Changes

Postby Christine Honda 2I » Sun Jan 26, 2020 8:05 pm

If the substance is not in the most stable/standard phases then you must use the total of the enthalpy of the phase change and the bond enthalpy when calculating.

Chris Charton 1B
Posts: 69
Joined: Mon Jun 17, 2019 7:23 am

Re: Phase Changes

Postby Chris Charton 1B » Sun Jan 26, 2020 8:32 pm

When the substance is not in its standard state at the given temperature, you have to add the enthalpy of its phase changes. For example if its a gas in its standard state and is currently a solid, you would have to add the enthalpy of its sublimation.

405268063
Posts: 102
Joined: Thu Jul 25, 2019 12:17 am

Re: Phase Changes

Postby 405268063 » Sun Jan 26, 2020 8:47 pm

Yes, as the previous response said, you must add the enthalpy of the phase change.

rohun2H
Posts: 100
Joined: Wed Sep 18, 2019 12:19 am

Re: Phase Changes

Postby rohun2H » Sun Jan 26, 2020 8:56 pm

Add the enthalpy of the phase change.

gabbymaraziti
Posts: 111
Joined: Wed Sep 18, 2019 12:19 am

Re: Phase Changes

Postby gabbymaraziti » Sun Jan 26, 2020 8:58 pm

You should calculate the enthalpy, then add the enthalpy of the phase change.

Eesha Chattopadhyay 2K
Posts: 104
Joined: Fri Aug 09, 2019 12:16 am

Re: Phase Changes

Postby Eesha Chattopadhyay 2K » Sun Jan 26, 2020 9:13 pm

The proper method is to calculate the enthalpy, then add the enthalpy of the phase change.

Joowon Seo 3A
Posts: 100
Joined: Sat Aug 24, 2019 12:17 am

Re: Phase Changes

Postby Joowon Seo 3A » Sun Jan 26, 2020 10:28 pm

To accommodate for the phase change of the material, add the reaction enthalpy of the phase change onto the reaction.


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