JR

FYI, I bounced this off a colleague of mine who knows a lot more about detonation than I do. His reply to the question "what would the products look like?" was: "A ball of mush." Whatever is in there lies in parts of the phase diagrams probably not well understood, and certainly a lot of dissociated species (H, OH, etc. etc) as YT mentioned. He also said that he saw this very thing in a book that was written in the 1950's. I don't have the name of the book; heck, it's probably out of print anyway.

One point I thought of a little bit ago ... all the species were are considering at 1000 kelvin and 55,000 psi would be supercritical, so not really gas or liquid. (We were both right!!! ) Critical Temp - H2O: 374 C Critical Press - H2O: 3212 psi Critical Temp - CO2: 31.1 C Critical Press - CO2: 1072 psi Critical Temp - N2: -146 C Critical Press - N2: 485 psi Critical Temp - O2: -118 C Critical Press - O2: 735 psi So, I don't really know what the phase diagrams for these compounds look like at 55,000 psi. I do know that water does some really weird stuff at high pressure.

Well, one of my company's services is numerical modeling of detonation phenomena I'm pretty tied up with some other work right now, but maybe a bit later, I can set up this calculation and see what the numerical models 'say.'

I realize this is an older post, but I am quite familiar with GAMESS...use it all the time to compute structures and frequencies. Why don't you post your input file so we can have a look?

NG starts as a liquid, and therefore if not allowed to expand, the resultant products after reaction must also therefore be a liquid I don't think that's true at all. It is a liquid because (a) compared to the size of the molecular products, the reactant liquid molecules are quite large and (b) the reactant molecules interact with other quite strongly. After decomposition, if the products are considered to be mostly N2 and CO2, the intermolecular interactions (which determine gas, liquid or solid) are relatively weak; these are gases. The liquid is initially filling the cavity, but it is not under pressure. After reaction, the chemical composition of the material inside the cavity is different. It is perfectly reasonable for the liquid to occupy 'all available' space in the cavity, but the reaction products to be a gas. 'All available' space in the cavity is a relative term, too. The reacting medium molecules exclude considerable space that are not formally occupied by mass. To visualize this (I know NG does not have phenyl rings, this is just for illustration), consider for a second liquid benzene. There is a lot of space inside the ring (and above and below it) that is excluded from being occupied by other benzene molecules. However, if the benzene were to decompose to C and H2, the excluded space is MUCH less, so the 'effective' available volume to the products is much greater. When we numerically model detonations, one of the parameters needed is the 'covolume' of the products ... that is, the volume occupied by the molecules rotating in three dimensions. This defines the excluded volume, which in turn when subtracted from total volume, defines the available product volume. It is a tricky modeling problem, since volume is variable, along with temperature and pressure and moles of products (hey, that's all the gas law parameters that can vary!) depending on how much of which product is produced. however some of these liquid may re-combine to form acids or even solids (it`s under extreme pressure remember). Well, I am asserting that the pressure is not THAT high after the shock wave passes, which it does quickly. The wave hits the steel, then dissipates. The final thermodynamic state inside the cavity is just not that extreme. Let's play with some numbers, just to get 'an idea (for this back of envelope calculation, I am ignoring sig figs):' (1) assume NG decomposes to H2O, CO2, N2 and O2 4 C3H5N3O9 --> 10 H2O + 12 CO2 + 6 N2 + O2 or 4 moles of solid produces 29 moles of gas. (2) the density of NG is 1.59 g/cm^3, so to fit 2g, we'll need a cavity of 1.26 cm^3 = 0.00126 L. (3) let's say product state temperature is 1000 kelvin. NG detonates at 3470 kelvin, but that is T INSIDE shock. (4) let's assume Ideal Gas Law, just for simplicity. These assumptions, except for the temperature one, will give us an UPPER limit of pressure inside the cavity. Molar Mass NG = 227 g/mol 2g NG = 0.0088 mol 0.0088 mol solid reactant = 0.06 mol gaseous products p = nRT/V p = (0.06 mol)(0.08206 L atm/mol K)(1000 K)/(0.00126 L) p = 3908 atm, which is about 55,000 psi. 55,000 psi is about what is present inside a high powered rifle (such as 30-06 Springfield) chamber when the gun is fired. This activity is done all the time without producing outlandish products and results, or even condensation of the product gases. You may get a higher than this, sure, but I maintain my hypothesis that you won't get so high to produce the kinds of effects being considered. But hey, that's the fun the thing about hypotheses..they are, after all, just guesses!!

and so, the NG starts detonation reaction, it obviously can not become a gas as that requires more room for molecular freedom. Well, that's my point. There is PLENTY of room in the cavity for the gaseous products. 2 g or so of NG will not produce THAT much gas. The gaseous products are expanding from the highly compressed explosive (NG or whatever) in the shock, that's where the super high pressure is. the temp is roughly 7000K (well above the vaporisation point of Tungsten), and the products are all gaseous. The temp is only that high IN the shock wave itself, which does not last for a very long time at any given point in space. The net heating of the bulk material is actually quite small. ANFO detonates at relatively low temp (not because it is 'heaving' or low brisance), and other high ex's like RDX are similar, though admittedly higher final temp than ANFO. I don't have my book of such data within reach at the moment, or I'd give some numbers. so in YOUR esstimation, what may (maynot) happen? I think you will detonate the hi-ex and have a cavity containing compressed (but not extraordinarily so) gas. If the material can withstand the conditions of the detonation itself (megabar shock wave), than it certainly will withstand the expanded product gases. I don't think the products will condense (these gases get compressed in cylinders several hundred atmospheres and don't condense, they are not polar and van der Waals forces are not so great).

lol @ Rad JR, I understand exactly what you`re saying. I wasn`t thinking along the lines of AN, ANMN,ANFO ect... they`re just heaving charges, I was considering along the lines of a Primary, Fulminates, Azides, double salts, picrates etc... and only in small quantities hence the use of a primaries as opposed to a secondary that require shockwave propagation. and only a gram or 2 at that The physics of shock propagation are the same whether primary or secondary explosive. The only difference between primary and secondary is the ease with which the shock can get started. Primaries can go by thermal heating, secondaries require a detonation shock to sufficiently compress for propagating reaction to occur. the DV`s actualy irrelevent as the object isn`t to break the steel container, but convert the explosive to gas (as they all do) but have that gas so under pressure, that it would be forced to do something? either liquify or make a solid due to the molecules not being able to be far enough appart to exist as a gas. it`s basicly the Irrisistable force verses the imovable object, but on a practical scale and not quite literal From what I understand the two thermodynamic states that have to be considered are: initial = conditions insides the shock wave, final = reaction products just after the shock wave passes. Inside the shock, the pressure is of the order of megabar and the temperature is say 4000 kelvin. After the shock passes, the pressure is related to moles of gas and volume of cavity (but Ideal Gas Law usually doesn't work here, of course) and temperature is say 1000 kelvin or less. Therefore, compared to the initial state, the final products have expanded. You would have a spherical cavity with some reasonably high pressure gas, but it really would not be something super extraordinary. Other than the size of the cavity, this is not so different from the controlled detonation trailers used by bomb squads. One EOD dude told me that after they let something go inside, the vent holes whistle for several days. Amazing. But compared to the 'gas state' in the shock itself (ie, after chemical reaction but before the shock passes), the cavity, though 'full' of explosive, is plenty of volume for the gaseous products. In your 'back of the envelope' scenario, you had about 2 g of explosive in the cubic centimeter cavity; assume complete conversion to gases, and compute how many moles of gas there are using a temperature of about 1000 kelvin, or even 2000 kelvin (use IGL as a starting point). The pressure inside the cavity after the explosion again will be high, but not 'out of this world.' Finally, if you use a primary explosive such as one of the inorganic salts (fulminate, azide, etc), your products will contain solids as well as gases (even secondary high explosives contain solid carbon products, that one of the things that makes numerical modeling of their detonation difficult), so your gas production is relatively smaller. Two Cents Worth, if that much....

Well, let's see if we can noodle some stuff out on this. Detonation is a hydrodynamically mediated process, not chemically mediated. Essentially, this means that in a detonating medium, the sole 'process' that governs what is happening is the motion of the shock wave through the medium. Detonation is shock propagation. So the question reduces to detonation or not? Well, that will solely depend on the initial impulse. If the initial impulse (the spark, for example) sufficiently compresses the explosive for shock propagation to occur, it will detonate. Otherwise, in these circumstances, probably not much will happen. Pressures in the shock wave for common explosives are in the megabar range, which likely far exceeds the pressure of gaseous components in the container volume. Therefore, if detonation occurs (and it will, provided a large enough impulse is given), all gaseous products will expand out of the shock wave. Lot's of detonation temperatures are very low (I believe ammonium nitrate, for example, detonates around 400-450 celsius), which is NOT the same thing as the shock temperature (which is generally thousands of kelvins). The result, therefore, would be the gases in the volume at some 'warm' temperature and elevated pressure. Like all explosions, there would be some unexploded explosive remaining. Does the resulting detonation shock have enough 'ummmff' to damage the container? Depends on the amount of explosive and detonation velocity (the property called brisance). Low brisance detonations (such as ammonium nitrate) tend to not have sufficient shattering power to fracture steel (except in very, very large quantities, where the shear 'weight' of the shock front can cause damage). I don't recall the precise number, but I THINK the threshhold for shattering steel is around 7000 or 7500 m/s detonation velocity (and a small amount of hi-ex would lack the power to do any noticeable damage - MAYBE some surface spalling, if that). Finally, I think nitroglycerine is a liquid, so it would not be a perfect crystal in the cavity (under ordinary conditions). These are just my opinions, based on what I THINK I understand about explosions.