Hatrack River Writers Workshop: Chemistry question

This is topic Chemistry question in forum Open Discussions About Writing at Hatrack River Writers Workshop.

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Posted by Alye (Member # 5017) on :

I need an explosion. Something that will react violently with just a drop of gasoline.

I have a character who needs to die in a explosion. What I want is a viscous fluid leak out of a nearby trashcan as she is filling up her car with gas as she takes out the nozzle a single drop falls to the ground. Kaboom or fire.

The fluid can be any color as its coming out of a trash can. I would prefer a non foul smelling order.

If there isn’t anything like this, ok. I’ll make something up but I would like to keep it as real as possible.

Posted by rickfisher (Member # 1214) on :

I can't help with the situation as you've described it, but I have to say that if this is supposed to be a realistic story (i.e., not fantasy) and you "make something up", your story is dead. Even if it's SF--you can make something up, but you'll need at least a mention of the type of chemical reaction involved.

If it's fantasy, of course, the explosion can be caused by magic, as long as it fits into your magical system.

Does it have to be set off by the combination of a drop of gasoline and gunk leaking from a trashcan?

Posted by KPKilburn (Member # 6876) on :

If you want to be realistic, then you have to consider the physics of an explosion. Unless the material is a high explosive like C4 or TNT, then it probably should be in a container (like a gas tank) when it ignites in order to build up pressure and explode. Does it have to be gas dropping onto something?

I recommend you start here...

http://en.wikipedia.org/wiki/Explosion

http://en.wikipedia.org/wiki/Explosive_material

Posted by Grovekeeper (Member # 5650) on :

KPK is right. Low-order explosives, like black powder and gasoline vapor, aren't really explosive at all; they just burn really fast. For them to "explode", they need to be contained for a presure buildup; once the pressure vessel breaks, all of the pressure is released at once, and that's the "explosion".

To make a convincing low-order explosion, you'd need a lot of whatever it is that's going to be reacting. Gasoline vapors will ignite quite spectacularly, but unless you have an enclosed space, they'll either dissipate or just burn off, rather than making an earth-shattering kaboom.

High-order explosives are another matter entirely; they don't burn at all. They are composed of a material that is physically or chemically unstable, and would "rather" be in a more stable state. Whatever trigger sets it off does so by causing a little of the material to get over its energy hump and break apart. The energy released from that little bit causes more of the material to break down, and what you end up getting is a shockwave of destabilization traveling through the material faster than the speed of sound. This is called "detonation".

Unless you're planning on creating (and explaining) entirely new physics for this scene, any gasoline-and-trickle-of-chemicals explosion is going to act as a bungee cord for any reader who knows about this sort of thing.

-G

Posted by KayTi (Member # 5137) on :

You could use that static-electricity gasoline ka-boom thing that happens very rarely in the winter...

Posted by AstroStewart (Member # 2597) on :

I second KayTi's suggestion.

It is physically plausible that your character, instead of accidentally dropping gasoline into some magical explosive fluid on the ground when she removes the nozzle, could instead kill herself by accidental discharge of static electricity. With the gas-cap still off, after she returns the nozzle to its holster, she could turn to fasten the gas cap back in place, but accidentally have some buildup of static electric charge on her fingertips, which could then ignite the fumes coming out of her gastank. This could start a chain reaction that could ignite the fuel in the gas tank and BOOM --- explosion.

(I actually watched an episode of myth-busters, which is agreat show btw, on discovery channel, where they were challenging the myth that cellular phone transmissions could accidentally cause an explosion at the gas tank, thus requiring all the warning signs you see at the pump which read "turn off cell phones" etc. They were unsuccessful in trying to make the car explode with cell phone signals. However, they did manage to set the car off with a static electric charge on the dummy person as they handled the nozzle/gascap area. So it is definitely within the realm of possiblity as the source of an accidental gas-explosion-death.)

Posted by Rommel Fenrir Wolf II (Member # 4199) on :

JP8 deasal and 15-40 OIL

a form of napome. burns hotter when water is applied.

although a inition sorce is needed, a spark, match, etc.

RFW2nd

Posted by KPKilburn (Member # 6876) on :

quote:
However, they did manage to set the car off with a static electric charge on the dummy person as they handled the nozzle/gascap area. So it is definitely within the realm of possiblity as the source of an accidental gas-explosion-death.)

If I recall correctly, I believe they enclosed the test dummy in plexiglass in order to create the conditions for an explosion since in open air it would simply ignite.

In movies, I think you can get away with the car crashing and exploding because of the visual effect. I'd think it would require a little more explanation in a book.

From the context of the original post, I can't tell exactly what's going on, but I'd recommend that if you want an explosion, then make it believable by adding a build up - e.g., a woman is pumping gas, gets caught up in a shootout that ruptures the gas line (you have to understand that a gas pump has safety shutoffs for things like this, so think it through), she's trapped by fire, it consumes the rack of propane tanks nearby, the tanks reach their temperature limit and BOOM!

Maybe not the best thought-out example, but I think it would be more credible than gas mixing with something and exploding.

Posted by smncameron (Member # 7392) on :

Why not just cut out the middle-man and go for spontaneous human combustion?

I'm not a chemist, but if you want to go the cliched route you could always make your character a smoker.

Posted by annepin (Member # 5952) on :

Some negligent fool could have a barrel with just a little gasoline in it, enough to evaporate and build up pressure within the barrel. If the sun hits it, the pressure will be even more. Then you need a spark of some kind... Not sure how big the explosion would be, though.

Posted by Tricia V (Member # 6324) on :

Maybe she drops her cell phone and the battery comes out and that helps ignite things.

The thing is, a gas pump is designed to allow any moron to dispense a highly flammable substance regularly in a safe manner. So it's actually a very unlikely place for someone to die a fiery death.

Posted by Alye (Member # 5017) on :

its to be a murder so I have a bit of leeway in how it is to happen. I just want it to look like an acident. =) and thanks for all the sugestions

Posted by halogen (Member # 6494) on :

That is a rather elaborate murder. I'd go with something more casual, what about carbon monoxide poisoning (while driving)? It isn't explosive but it might be more plausible.

Posted by jaycloomis (Member # 7193) on :

Let your characters lead the plot, don't pull them by a leash. This scenario is dripping with unlikely events that only exist to benefit the plot and your planned outcome. Try and think of your characters as real people, and your world as a real world, where things happen most logically and, if a death is necessary, let it happen in a more believable manner.