What is the Standard State of Carbon?

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The discussion focuses on identifying the standard state of carbon between graphite and diamond. It references the enthalpy changes associated with the combustion of both forms of carbon, indicating that graphite has a ΔH of -393.5 kJ/mol while diamond has a ΔH of -393.4 kJ/mol. The speaker applies Hess' Law to determine that converting graphite to diamond requires an energy input of 0.1 kJ/mol, suggesting that graphite is the more stable form due to its lower energy content. The conclusion drawn is that graphite is considered the standard state of carbon. Understanding these energy dynamics is crucial for determining stability in carbon allotropes.
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Homework Statement



Graphite can be change into diamond according to the following equation:

Cgraphite ==> Cdiamond

Consider the following reaction equations:

Cgraphite + O2 (g) ==> CO2 (g) ΔH = -393.5 kJ/mol

Cdiamond + O2 (g) ==> CO2 (g) ΔH = -393.4 kJ/mol

Which form of carbon - graphite or carbon - is considered the standard state of carbon?

2. The attempt at a solution

I tried to use Hess' Law of Summation and determined that to go from graphite to diamond, it takes -0.1 kJ/mol.

To go from diamond to graphite, it takes 0.1 kJ/mol.

I don't know how I can use this information to determine the standard state.
 
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The one with lower energy content is the more stable one.
 
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