When to leave out reactants/products from enthalpy calculations

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Nick Fiorentino 1E
Posts: 102
Joined: Wed Sep 18, 2019 12:16 am

When to leave out reactants/products from enthalpy calculations

Postby Nick Fiorentino 1E » Fri Jan 31, 2020 7:08 pm

How do you know when a compound is in its purest form, aka when it won't impact enthalpy change?

VPatankar_2L
Posts: 104
Joined: Thu Jul 25, 2019 12:17 am
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Re: When to leave out reactants/products from enthalpy calculations

Postby VPatankar_2L » Fri Jan 31, 2020 7:45 pm

A compound is in its purest form when it is in its most stable form. An example of this is O2 which has an enthalpy of formation of zero because it is the most stable form of oxygen, whereas O3 would have an enthalpy of formation that was not equal to zero. Generally, gases are in their most stable form but a substance like carbon can be in its most stable form as solid graphite.

Hui Qiao Wu 1I
Posts: 56
Joined: Fri Aug 30, 2019 12:16 am

Re: When to leave out reactants/products from enthalpy calculations

Postby Hui Qiao Wu 1I » Sun Feb 02, 2020 9:58 am

To add on, the most stable forms won't affect enthalpy change only when calculating the enthalpy of formation.

Caroline Zepecki
Posts: 101
Joined: Fri Aug 09, 2019 12:16 am

Re: When to leave out reactants/products from enthalpy calculations

Postby Caroline Zepecki » Sun Feb 02, 2020 10:16 am

Can you assume that inert gasses wouldn't affect enthalpy calculations then?

Jasmine 2C
Posts: 184
Joined: Wed Sep 18, 2019 12:18 am

Re: When to leave out reactants/products from enthalpy calculations

Postby Jasmine 2C » Sun Feb 02, 2020 10:57 am

I believe Dr Lavelle gave a list of gases that are in the purest form (O2, N2, etc). I think there should be a list in the textbook.


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