Standard enthelpies of formation of carbon nanotubes etc.

In summary, the standard enthalpies of formation for carbon nanotubes, diamond, carbon buckyballs, and graphene are small, according to information from physics forums. However, this seems odd given that diamond and other exotic carbon allotropes, which have similar bulk moduli, are formed under extreme pressures and temperatures deep beneath the Earth's surface. The conversation continues with a clarification on the molar metric and the mention of highly technical papers. It is then explained that while the enthalpy of formation for diamond is small, the energy barrier between diamond and graphite is significant, requiring a lot of energy to convert between the two.
  • #1
James Essig
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TL;DR Summary
I am curious about the standard enthalpies of formation of carbon nanotubes, diamond, carbon buckyballs, graphene, etc.
I am curious about the standard enthalpies of formation of carbon nanotubes, diamond, carbon buckyballs, graphene, etc. I read from physics forums that the standard enthalpies of formation of these allotropes of carbon are small. However, since diamond is fabricated naturally under extreme pressures and high temperatures at depths of at least dozens of kilometers below the Earth's surface, small magnitude enthalpies of formation do not make much sense to me for diamond and thus also for the other exotic carbon allotropes I mentioned above all of which have similar bulk moduli. If anyone can offer some information on this subject that would be great. I've looked at some of the papers available on line for this kind of stuff but I find them obtusely technical. I am not adverse to reading highly technical papers of the subject so long as I know they are rigorously peer reviewed and of high research qualities. By molar standard enthalpies of formation I am assuming that the molar metric is for one mole of carbon atoms and not, say, one mole of carbon nanotubes and the like.
 
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  • #2
The enthalpy of formation of diamond is small (I want to say it’s something like 2.5 kJ/mol relative to graphite), but the energy barrier between diamond and graphite is huge (something like 1000kJ/mol). So getting from diamond to graphite requires a LOT of energy, even if thermodynamically the energies aren’t that different.
 
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Likes jim mcnamara
  • #3
Thanks for the reply TeethWhitener. That is useful information.
 

Related to Standard enthelpies of formation of carbon nanotubes etc.

1. What are standard enthalpies of formation?

Standard enthalpies of formation (ΔH°f) are a measure of the heat released or absorbed during the formation of a compound from its constituent elements in their standard states (usually at 25°C and 1 atm). It is a thermodynamic property that helps determine the stability and energy content of a substance.

2. How are standard enthalpies of formation determined?

Standard enthalpies of formation are typically determined through experiments using calorimetry, where the heat released or absorbed during a chemical reaction is measured. The values can also be calculated using theoretical methods, such as quantum chemistry calculations.

3. What are carbon nanotubes?

Carbon nanotubes are cylindrical structures made up of carbon atoms arranged in a hexagonal lattice. They have a high aspect ratio (length to diameter ratio) and possess unique mechanical, electrical, and thermal properties, making them useful in a variety of applications.

4. How are carbon nanotubes formed?

Carbon nanotubes can be formed through several methods, including chemical vapor deposition, arc discharge, and laser ablation. These methods involve the use of carbon-containing gases or solid carbon sources, which are heated to high temperatures to produce the nanotubes.

5. What is the significance of standard enthalpies of formation in relation to carbon nanotubes?

Standard enthalpies of formation play a crucial role in understanding the thermodynamic stability and energy content of carbon nanotubes. These values can help predict the conditions under which the nanotubes will form and provide insights into their potential applications. Additionally, knowing the standard enthalpies of formation can aid in the design and synthesis of new carbon nanotube structures with desired properties.

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