BASF
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heat capacity of Sorguyl
I´m looking for the value for Cv or Cp for Tetranitroglycoluril, which i need for the calculation of detonation pressure.
I did a search on NIST, but only the value for HMX was available.
It´s a pity i forgort my physics-book at home......wasn´t there a method to estimate heat capacities of solids?
I remember something vaguely like it was 2,5 J/mol K or something like this which was said could be used as a rough estimation-value.
I would be grateful for any info on this.
HLR
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I am a fish
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You're probably thinking of the Dulong-Petit formula...
C = 3NR
Where...
C = heat capacity
N = Moles of atoms
R = Ideal Gas Constant (8.3145 J / K)
Remember that this is only a classical approximation and may be wildly inaccurate in certain cases (e.g. diamond).
If you require something better, look up 'Debye Model'.
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BASF
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Thanks a lot !
- Thats it. I know rough means really rough in this case......thanks for the hint on the "debye-model", i´ll try that.
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Microtek
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I think you should use the tabulated value of a somewhat similar material. And a heat capacity of 25 J/K*mol doesn't seem right at all when
talking about solids ( for HMX the actual value is about 290 J/K*mol ), so maybe C = 3NR goes for gases ?
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I am a fish
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| Quote: | Originally posted by Microtek
I think you should use the tabulated value of a somewhat similar material. And a heat capacity of 25 J/K*mol doesn't seem right at all when
talking about solids ( for HMX the actual value is about 290 J/K*mol ), so maybe C = 3NR goes for gases ? |
It's for solids. It just doesn't work in this case.
1f `/0u (4|\\| |234d 7|-|15, `/0u |234||`/ |\\|33d 70 937 0u7 /\\/\\0|23.
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Dany
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The heat capacity at constant pressure Cp of Sorguyl (TNGU) is 67.8 cal mol−1 K−1 (or 283.67 J
mol-1 K-1) (@ T= 300 K ). This value is calculated theoretically using Ab initio quantum chemical method. in the attached file
you will find other interesting properties for many other energetic materials (42 compounds) such as gaseous enthalpy of formation, Cp and
S0 (entropie).
Dany.
Attachment: Ab initio quantum chemical predictions.pdf (181kB)
This file has been downloaded 610 times
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Dornier 335A
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I fail to see why the heat capacity of an explosive is necessary for calculating its detonation pressure. Could you explain?
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watson.fawkes
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Energy liberated has to
go somewhere. The more it goes into heating the solid material prior to reaction, the less is available to other modes, such as the energy of a
pressurized gas.
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