Sir_Gawain
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Registered: 12-10-2022
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Calculating the heat of explosion of ETN
Since learning about calculating the enthalpy of a reaction, I wanted to try to calculate the energy released upon the detonation of an explosive
material, ETN in particular. The understanding that I have of this is to add up the bond formation energies of the reactant and subtract it from that
of the products(I used this table). In the case of ETN I calculated a total enthalpy of formation of 8987 kJ/mol (3 C-C, 4 C-O, 6 C-H, 8 N-O, 4 N=O). That of the
products was 11323.5 kJ. The calculated heat of explosion was 2336.5 kJ/mol.
Did I do this correctly? Some complications were the resonant bonding in the nitrate group. I counted it as 2 single bonds and one double bond, but
would those bonds be of average strength?
I calculated the number of bonds based on this formula
2C4H6N4O12 → 8CO2 + 6H2O + 4N2 + O2
then halved the energy.
“Alchemy is trying to turn things yellow; chemistry is trying to avoid things turning yellow.” -Tom deP.
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Rainwater
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Registered: 22-12-2021
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Not sure. So lets break it down. Folowing this procedure
Link
Using the lewis structure from Wikipedia
4 NO3 groups on a 4 carbon alkane.
Each NO3 group has
(2)single O-N = 201 × 2 = 402
(1)double O=N = 607 × 1 = 607
(1)single O-C = 358 × 1 = 358
Total NO3 = 1,367
The alkane has
(3) C-C = 347 × 3 = 1041
(6) C-H = 413 × 6 = 2478
Total = 3519
1367 × 4 + 3519 = 8987
Looks like the first half is correct
[Edited on 20-4-2023 by Rainwater]
"You can't do that" - challenge accepted
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