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Instant Water Boiling

All non-spudgun related discussion goes here such as projects, theories, serious questions, etc. All "off-topic" posts (aka useless posting, determined by moderators) will be removed.
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Unread postAuthor: john bunsenburner » Wed Oct 29, 2008 4:39 pm

No electrolosis of NaCl(aq) is wrong becuase instead of getting oxegen from the water you are getting clorine which (though explosive with hydrogen, making hydrogen cloride(HCl) which is the gas used o make hydrocloric acid), is not the desirable type of electrolosis. Thurther more this kind of electrolosis is dangerous and not very efficient. When it comes to steam powered rifles i have two ideas for you:

1.have a chanber that is either electically or otherwise heated. fill it with water and attach a ball valve, regulator and check valve at the top and a thermometer at the bottom. have a tube connected to your chambre when desired temperatures and preasures have bin reached you open the ball valve(or what ever valve you choose for that matter) hot steam bursts out and pushes the projectile out while condensed water flows back to the main boiling chamber

2. use super heated water which you dump into a chamber whith a check valve and then set of with something, this technique is dangerous and not very lickly to work
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Unread postAuthor: TurboSuper » Wed Oct 29, 2008 4:56 pm

Put the water in an airtight chamber and vacuum out any air inside.
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Unread postAuthor: LikimysCrotchus5 » Wed Oct 29, 2008 5:04 pm

john bunsenburner wrote:No electrolosis of NaCl(aq) is wrong becuase instead of getting oxegen from the water you are getting clorine which (though explosive with hydrogen, making hydrogen cloride(HCl) which is the gas used o make hydrocloric acid), is not the desirable type of electrolosis. Thurther more this kind of electrolosis is dangerous and not very efficient. When it comes to steam powered rifles i have two ideas for you:



No, thats wrong. I really dont think there is anything called hydrogen chloride gas. That is hydrochloric acid, which is aqueous.

When using NaCl as a electrolyte, chlorine gas is produced, which is the reason why its not used (unless you want to die from chlorine gas (enough of it will)).

TurboSuper wrote:Put the water in an airtight chamber and vacuum out any air inside.


As i already mentioned :)
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Unread postAuthor: rp181 » Wed Oct 29, 2008 5:27 pm

john: Its not "wrong" in that case, explosives are "wrong" but when hyou want to blow something up, it is "right". Salt is perfectly fine if you need HCLl, a chemical reaction or physics can never be "wrong", it just is there, how you put it into use is another story. Its also not "wrong" for this application, it still combusts, just with more toxic by products (that isnt even that concentrated). The only issue is acid corroding the chamber or chemial breakdown.
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Unread postAuthor: DYI » Wed Oct 29, 2008 6:51 pm

No, thats wrong. I really dont think there is anything called hydrogen chloride gas. That is hydrochloric acid, which is aqueous.


HCl will only stay in solution with water up to about 40% or so, after that it starts off-gassing. So, at SATP, pure HCl is a gas. You can get tanks of pressurised HCl just like you can get oxygen and nitrogen and such (although it's heavily regulated, for what are hopefully obvious reasons).

I think the aim here is to pressurise a chamber with steam, in which case the idea of pulling a vacuum isn't of much use. If the OP is really serious about a good steam gun/boiler, electric is the way to go for any small or handheld designs. If you're going for something more like the Mythbusters made (about 30 feet long and firing a 24 lb ball, just FYI), then external combustion may be more practical (relatively speaking, of course :roll: ).

You could, of course, pressurize the chamber with the products of electrolysis of water, but it wouldn't be terribly efficient or safe.
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Unread postAuthor: Ragnarok » Wed Oct 29, 2008 6:57 pm

LikimysCrotchus5 wrote:I really dont think there is anything called hydrogen chloride gas. That is hydrochloric acid, which is aqueous.

He's perfectly correct, it can exist as a gas. However, it's not acidic as a gas, only in aqueous solution does it become an acid. It needs to dissociate into hydroxonium and chlorine ions to become acidic.

...Holy CRAP, I remembered some of my Chemistry A-level! :D

I agree, using salt as an electrolyte is a poor choice IF you want Hydrogen and oxygen, but using salt in this case would still provide an electrolyte that would cause the water to break down under current, as such, it is not "wrong".
The point of discussion was not getting Brown's Gas, it was the fact the water would break apart rather than boil.

It's worth noting however, that subjected to voltages of somewhere above 1000V (I believe), water flash "boils", and can be turned to plasma, where it stays until the voltage/current (can't remember which) falls too low.

As such, Electrothermal cannons can use water as a "fuel".

If that's not rapid enough, I don't know what the hell is.
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Unread postAuthor: LikimysCrotchus5 » Wed Oct 29, 2008 7:25 pm

I stand corrected then. Still haven't learned that in chem 2. Im learning oxidation and reduction reactions, which electrolysis has a oxidation and reduction reaction.

So what is defined as SATP, i looked on wikipedia and it gave me a bunch of different numbers so im not sure which one you are referring to.
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Unread postAuthor: mega_swordman » Wed Oct 29, 2008 7:33 pm

Thank you everybody. In terms of quickly boiling water, I have altered my design.

Biopyro wrote:It would just add an extra heat source, of which half of the heat would be radiated into the surrounding air. The most efficient convenient way is a pressure cooker, since it stops the energy evaporating out, and it's insulated to prevent it radiating out.


In regards to my coil idea on the outside, I considered what Biopyro stated above. Thus, it would be more logical to place a heated coil inside the body of water.

LikimysCrotchus5 wrote: It takes about 100 degrees Celsius to boil water at 101.3 kPa. Now, if you create a vacuum, the intermolecular forces overcome themselves and they rip apart, causing the water to boil because there is no pressure holding the molecules together.


Likewise, I considered the idea of placing water inside a vacuum. This makes sense for this idea is seen in application at higher altitutes (just look at cooking instructions for higher altitudes).

Therefore, my new idea uses both of these principles (Figure 2). It has an internal coil so that all heat will be transferred directly to the water and no heat will be lost to the air. Furthermore, the attached vacuum with remove all the air and allow for the water to boil faster.

Any further comments or suggestions will be appreciated.
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Unread postAuthor: LikimysCrotchus5 » Wed Oct 29, 2008 7:37 pm

Seems like it would work but what are you trying to get here?

Do you want steam? Because the vacuum will surely suck that out. But it will make it boil fast for sure.
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Unread postAuthor: rp181 » Wed Oct 29, 2008 9:08 pm

if its for a gun, drawing a vacume is pointless. You just vacuming it only to bring it back up to atmospheric pressure (less).
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Unread postAuthor: mega_swordman » Wed Oct 29, 2008 10:22 pm

I stated earlier that this was just a project I wanted to do to see if I could boil water very quickly. Steam was not in mind.

Thanks for the help everyone.

EDIT: I came to the realization that if the vacuum was removed, this would essentially be a small fire tube boiler. To whom it may concern, this could produce steam if you remove the vacuum.
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Unread postAuthor: Hotwired » Wed Oct 29, 2008 11:03 pm

Is the lower boiling temperature due to the vacuum ok for the project?
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Unread postAuthor: POLAND_SPUD » Thu Oct 30, 2008 1:11 am

is the lower boiling temperature due to the vacuum ok for the project
of course it isn't
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Unread postAuthor: mega_swordman » Thu Oct 30, 2008 2:19 am

POLAND_SPUD wrote:
is the lower boiling temperature due to the vacuum ok for the project
of course it isn't


I am not quite sure what is being said here. Perhaps the question needs to be reiterated.
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Unread postAuthor: Ragnarok » Thu Oct 30, 2008 4:26 am

mega_swordman wrote:I am not quite sure what is being said here. Perhaps the question needs to be reiterated.

Producing a vacuum reduces boiling temperature.

Rather than boiling at 100 degrees C, it will boil at say... 80 or 90 because of the lower pressure - Removing the vacuum will stop the water boiling.

The question is... do you want boiling water (That is, water in a gaseous form) by any means - and that which only exists in a partial vacuum - or do you want water at 100 degrees C?
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