Practical Chemistry in Writing: "Fire Lake" Concept

[klope3]

Extension of this thread: http://www.scienceforums.net/forum/showthread.php?t=35756

 

I'm back with another concept. In this medieval world that I've made (you've got to read the other thread to understand), it would be somewhat difficult to find pure sodium naturally, unless I write in some sort of mine. So I'm working on a concept I like to call "Fire Lake." I wanted to validate it with all you good people to verify its viability.

 

 

 

A warlike people with a fascination in what they call "earth magic" has invented a procedure for obtaining an extremely reactive material (pure sodium) for the purposes of explosives and incendiary battle tactics. Firstly, a small lake filled with salt water is found. The denser the concentration of salt, the better. Then a number of tall, solid iron spires are implanted in the lake bottom, possibly of varying heights.

 

A thunderstorm with plenty of lighting should make this concept work. If these solid iron spires rise high enough above other things, it seems, they will be hit by lightning, right? When that electricity hits a spire and tries to go down into the ground, it would electrify the salt water--albeit instantaneously--and, theoretically, separate the lake water into sodium and hydrochloric acid. This separation would be caused by the introduction of electrical energy to NaCl. When the salt splits into Na and Cl, the chlorine bonds with the hydrogen. Oxygen is released, along with H (one H is released from the two in water to form the acid), and the desired sodium settles to the bottom of the lake to be later harvested. I believe the event would be demonstrated by the below chemical equation. (I haven't learned enough yet to know how to show the presence of electricity in a chemical equation, if that's valid at all, so bear with me.)

 

H20 + NaCl + (electricity) --> HCl + Na + O + H

 

Now, the questions I need to ask concerning this include:

1) How likely is it that these spires will be struck by lightning during a lightning storm?

2) In the instant the lightning hits, would it be possible for the entire lake to be electrified?

3) Would the desired separation happen in such a brief moment, or would a sustained exposure to electricity be required?

[Flashman]

You've never dropped a lump of sodium in water?

[klope3]

What?

 

The point is, that's what they're trying to do. Once they have the sodium, they'll be able to use it against enemies offensively and defensively. If you mean that the sodium would just explode in the water after it was separated from the chlorine, that problem would be solved if the entire lake was turned into the acid and a layer of sodium.

 

I got this idea from a friend. In a chemistry class, a solution of salt water somehow got electrified (for a long or short duration, I do not know), and the result was HCl with a layer of Na on the bottom of the beaker. So based on those conditions, the Fire Lake concept should work if the entire lake were properly electrified all at once.

[Flashman]

http://www.gofish.com/player.gfp?gfid=30-1125747

[klope3]

Okay. So 12M HCl would be the best product for this situation. But would 12M HCl be produced under the conditions I'm suggesting? If 6M were produced, that really *would* be Fire Lake--but not in a good way!

 

I'm thinking that if 12M HCl were produced, boaters could go out into the water just after the strike and collect as much sodium as possible. A risky mission, of course, with another lightning strike impending at any moment, but that would just add to the drama, which is a good thing.

[hermanntrude]

nope

 

Although these are pretty extreme conditions you're describing and perhaps some sodium would be produced, most likely what'd happen is nothing. For electrolysis to work, the electricity needs to travel through the water as a continuous current. Both the anode and cathode need to be in the water. In the scenario you describe, the water is only one of the electrodes. The storm cloud being the other. Mostly, the current would be flowing through the air.

 

Also, when electricity is passed through salt water, the most common products are hydrogen and oxygen, although with a decent overpotential (high voltage) you can get chlorine gas too. I fure with the kinds of voltage involved in lightning, you might get some sodium but i'm not certain. Either way you'd get a lot more hydrogen than sodium.

 

Also, if you DID get sodium in any appreciable amount, it'd immediately explode on contact with the water in the pond.

 

I think this scenario is incredibly implausible. Also, using sodium as a weapon is crazily inefficient

[big314mp]

Why not use a home built battery and molten NaCl?

 

A proper furnace should melt NaCl, and surely your civilization can figure out how to build a battery of sorts.

[hermanntrude]

why bother though? much easier to make NO, or NO2 or Chlorine or HCN or gunpowder... all of which are deadly and viscious

[big314mp]

Well, from what I gather, the author had specific properties that needed to be met, and sodium fulfilled them the best.

[klope3]

Although these are pretty extreme conditions you're describing and perhaps some sodium would be produced, most likely what'd happen is nothing. For electrolysis to work, the electricity needs to travel through the water as a continuous current. Both the anode and cathode need to be in the water. In the scenario you describe, the water is only one of the electrodes. The storm cloud being the other. Mostly, the current would be flowing through the air.

 

Thanks. I needed that advice badly. I don't know anything about electrolysis, so it's good to have your input.

 

using sodium as a weapon is crazily inefficient

 

I knew that, but medieval warring cultures weren't always known for their efficiency. Catapults could also be crazily inefficient; they were difficult to aim, took alot longer to load than the bow, and were basically just meant to smash anything in their paths (friendly soldiers and enemies alike). Cannons were another example. Sometimes, both of these siege machines would be built on-site just before a battle--the catapults would be constructed and the cannons forged with molten metal and a shaped mold. They were so difficult to mobilize that often they would just be left right where they stood after the battle.

 

Okay, thanks for the advice. I'll have to think of some other crazy idea to pose to you all. I'm just glad I was stopped from doing this before I sort of made a fool of myself among scientific circles!

 

 

P.S. And if you hadn't gotten to me, the Mythbusters surely would've.

[Mr Skeptic]

Electrolysis is based on the amount of current passing through the water. A lightning bolt has very high voltage and comparatively little current, but all the excess voltage is wasted. They'd be better of using a water mill or wind mill attached to a generator, and doing electrolysis on molten salt.

 

As for its usefulness, imagine being stabbed with sodium. Ouch!

[jdurg]

As for its usefulness, imagine being stabbed with sodium. Ouch!

 

It'd be damned near impossible to make any type of penetrating weapon out of sodium. It would be like trying to stab someone with a stick of butter. You're not going to be able to penetrate skin, let alone clothing.

[hermanntrude]

you could, however make a knife out of steel and then run a channel down either side of it. Before you stab someone, fill the channel (groove) with sodium, or better still, potassium.

[Flashman]

With sodium projectiles you'd just have to splatter them against an enemies legs until he peed himself laughing...

[hermanntrude]

make a bullet with a sodium pellet in its wall? hollow tipped bullet with sodium in the hollow?