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Chemistry Forums for Students => Physical Chemistry Forum => Topic started by: kalyanvadagam on July 14, 2020, 02:45:11 AM

Title: Chemical energetics
Post by: kalyanvadagam on July 14, 2020, 02:45:11 AM
why is graphite the standard state of carbon why not diamond
Title: Re: Chemical energetics
Post by: Borek on July 14, 2020, 02:51:16 AM
What is the standard state? How are they chosen in general?
Title: Re: Chemical energetics
Post by: kalyanvadagam 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??????
Title: Re: Chemical energetics
Post by: Borek 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.
Title: Re: Chemical energetics
Post by: Enthalpy 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.
Title: Re: Chemical energetics
Post by: Borek 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).