227 
Sec. 7 -16- 
is normally of the order of 1000 Keal/Kg. Thus Tz is lowered by the 
inclusion of this dissociation to the extent of 0.3% but at the same time 
the mole number is increased and hence the pressure is creater. This ef- 
fect is of the order of 0.10% and hence the total effect on the detonation 
rate is (because of the square root relation) (3)(0.3-0.10)% = 0.10%. 
Similar calculetions show that the water dissociations: 2,0 = Hp + 20H and 
2llb0 = On + 2H are of small importance. Dissociations of oxygen and 
nitrogen are still more insignificant. 
b. Polyatomic molecules. Various polyatomic molecules have been 
reported in the gas samples withdrawn from bombs after detonation. Thus 
Schmidt reports CH, , CoH, HCN, CoNos NE, in variable but small amounts 
from almost all explosives. To allow for equilibrium formation of all these 
molecules seems mathematically an almost impossible task, particularly when 
it is considered that the thermodynamic functions of most of these moleculss 
are not too accurately known at the high temperatures in question. Ap- 
proximate calculations using ideal gas laws made on some of those which are 
found in greatest amounts indicate that the observed concentrations are in 
excess of equilibrium existing under the conditions of the detonation wave. 
In all probability these molecules are formed during the cooling process 
after detonation. But even when it is supposed that the analytical data 
represent the true conditions in the detonation wave, the formation of all 
these complex molecules does not alter greatly the results of calculation. 
Taking as an example the particularly unfavorable case of TNT for which 
the oxygen deficiency is large and the complex products particularly 
abundant according to Schmidt 2°one finds that in the formation of ali complex 
products reported by Schmidt a total of 8,7 Kcal of heat is absorbed per 
Kg. of TNT, while the total heat evolution is 375 Keal. At the same time 
the mole number of gaseous products is reduced feds 32.0 to 30.7 and there- 
fore the total effect on the detonation rate is approximately represented 
by the factor: [(30,7/526)(375/366.3)](4/2) = 0.965. The neglect of the 
complex products thus overestimates the rate by BIA; but it is believed 
that in general the corresponding error is smaller. 
c. Free hydrogen and carbon. The formation of free hydrogen in the 
detonation wave in the absence of solid carbon can be neglected because 
the equilibrium constant of the reaction H5O + CO = C05 + Hp ranges from 0,2 
at 3000° to 0.07 at 5000%K, Thus the greater part of the hydrogen is present 
as water and the formation of a few moles of free hydrogen per Kg of 
explosive is of little effect on the detonation rate. This follows because 
there is no mole number change in the reaction and the heat evolution is 
only 4.5 Keal. per mole at 3000° and is less at 5000°, The neglect of 
hydrogen in the absence of 8o0lid carbon causes therefore an underestimation 
of the rate by a few percent at most. 
In the presence of free carbon, on the other hand, the formation of 
free hydrogen will proceed almost quantitatively. The equilibrium constant 
of the reaction C + 150 = CO + Ey is about 10? Atm. at 3000°K and my be 
estimated as 5 x 10° Atm, at 5000°. Since the pressure (or fugacity, to 
be more correct) of oarbon monoxide in the detonation wave seldom rises 
