September 26, 2020, 05:37:19 AM
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Topic: Chemical energetics  (Read 617 times)

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Offline kalyanvadagam

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Chemical energetics
« on: July 14, 2020, 02:45:11 AM »
why is graphite the standard state of carbon why not diamond

Offline Borek

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Re: Chemical energetics
« Reply #1 on: July 14, 2020, 02:51:16 AM »
What is the standard state? How are they chosen in general?
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Offline kalyanvadagam

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Re: Chemical energetics
« Reply #2 on: July 14, 2020, 02:56:49 AM »
The question in the context of calculating enthalpy of formation.

For C(GRAPHITE) Enthalpy of formation is zero. But C(diamond) enthalpy of formation is nonzero.

Why??????

Offline Borek

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Re: Chemical energetics
« Reply #3 on: July 14, 2020, 04:13:49 AM »
These are two different forms, something must happen for the conversion to happen, it can't be thermodynamically neutral.
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Offline Enthalpy

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Re: Chemical energetics
« Reply #4 on: July 15, 2020, 08:09:51 AM »
Graphite is taken as the standard because it's more common. Diamond would be better reproducible, sure.

Offline Borek

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Re: Chemical energetics
« Reply #5 on: July 15, 2020, 01:01:52 PM »
Graphite is taken as the standard because it's more common.

I believe the more important point is that it is thermodynamically stable. Diamond is not (even if it is stable for kinetic reasons).
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