R. Meyer J. Köhler A. Homburg Explosives

Thermodynamic Calculation of Decomposition Reactions
In decomposition processes (detonation in the case of high explosives
or burning processes in the case of gunpowders and rocket propellants),
the kilogram CaHbOcNd is converted into one kilogram
n1 CO2 + n2 H2O + n3 N2 + n4 CO + n5 H2 + n6 NO.
In the case of industrial explosive with a positive W Oxygen Balance,
the occurrence of free oxygen O2, and in the case of explosive with a
very negative oxygen balance, e.g., TNT, the occurrence of elementary
carbon C have to be considered. If alkali metal salts such as NaNo3
are included, the carbonates of these are taken as reaction products,
e.g., Na2CO3. The alkaline earth components, e.g., CaNO3 are assumed
to form the oxides, e.g., CaO; chlorine will be converted into
HCl; sulfur into SO2.
Exact calculations on burning processes in rocket motors must include
dissociation phenomena; this is done on computer facilities (at leading
national institutes*), and the relevant industrial laboratories in this field
are nowadays equipped with computers and programs. The following
explanations are based on simplifying assumptions.
1. Conventional Performance Data of Industrial Explosives.
The explosion of an industrial explosive is considered as an isochoric
process, i.e. theoretically it is assumed that the explosion occurs
confined in undestroyable adiabatic environment. Most formulations
have a positive oxygen balance; conventionally it is assumed, that only
CO2, H2O, N2 and surplus O2 are formed. The reaction equation of the
example above is then
C8.19H40.48O37.39N18.73 =
8.19 CO2 + 40.48
2
h2O + 18.73
2 N2 + 1
40.48
(37.39 - 2 x 8.19 -
2 2 )O2 =
314
8.19 CO2 + 20.24 H2O + 9.37 N2 + 0.39 O2
The real composition of the explosion gases is slightly different; CO
and traces of NO are also formed.
1.1 Heat of explosion.
Table 33 also lists the enthalpies and energies of formation of the
explosives and their components.
* The data for the heat of explosion, the volume of explosion gases and specific
energy given in this book for the individual explosives have been calculated
with the aid of the “ICT-Code” in the Fraunhofer Institut für CHEMISCHE
TECHNOLOGIE, D-76318 Pfinztal, including consideration of the dissociation
phenomena. Therefore, the values have been changed in comparison to the
figures listed in the first edition of this book (computed without dissociation).