Creating an Endothermic Reaction Without Ammonium Nitrate

[quietbang]

So, I'm building a freeze ray, in a sense, and I was wondering...
What would the easiest/cheapest way to produce an endothermic reaction without using ammonium nitrate? The way I have the schematics so far is that I will have two substances that will blend just before exiting the ray, and therefore will react and freeze the substance it hits. My problem is that it needs to be viscuous enough- i.e, not solid- that it can be dispersed shortly after the reaction. It *also* needs to be cold enough to freeze an organic substance with sufficient liquid in a short amount of time.
Any ideas? Tips? Suggestions?
Keep in mind I'm a high school student who's income comes only from 10$ a pop tutoring sessions and occasionally winning stuff and who lives in the middle of a corn field, which means I am both very very cheap, far away from major cities (so the ability to order online is preferable- I have ammonium nitrate, we use it for fertiliser, but other than that..) and have access to my brother's tools, machinery, soddering iron, scrap metals, etc.
Thanks! :)

 

[JaredJames]

The simplest way to do what you want is to have something like liquid oxygen and spray that at an object.

I had a $3 can of compressed air for computer cleaning from a supermarket, which, if held close to an object for a few seconds would freeze it (would severely damage organic material). That was all from simple compressed air.

Note, the range is going to be limited to almost touching the device nozzle. It's also not going to look like in the movies.

I'd also add that damage to organic materials isn't reversible like in the movies, you can lose body parts doing this (think frostbite).

 

[Antiphon]

Liquid oxygen is dangerous in case of nearby combustion. Liquid nitrogen is cheap and poses no fire hazard.

I'd find a grade of silicone perhaps that can stay liquid at that temperature and mix it with the liquid nitrogen. It would be just like a flamethrower but opposite.

 

[JaredJames]

Liquid oxygen is dangerous in case of nearby combustion. Liquid nitrogen is cheap and poses no fire hazard.

I'd find a grade of silicone perhaps that can stay liquid at that temperature and mix it with the liquid nitrogen. It would be just like a flamethrower but opposite.

I didn't know if Nitrogen was useful for this purpose. If so, I'd certainly recommend it.

 

[Proton Soup]

you can buy various grades of "freeze spray" over the counter. some are designed for human use, some are not for human use.

 

[SkepticJ]

How quickly do liquid nitrogen or oxygen actually chill objects? Say someone hosed you down with it, how much would it actually take to freeze you? Wouldn't relatively small amounts of it just boil off you, taking some of your heat with it, but not actually hurting? Actually, the boiling itself would help to protect from more liquid contact, thanks to the Leidenfrost effect.

Boris' death in GoldenEye doesn't seem realistic to me. He'd have to be submerged in a bath of cryogenic liquid for probably well over ten seconds to freeze solid.

 

[JaredJames]

How quickly do liquid nitrogen or oxygen actually chill objects? Say someone hosed you down with it, how much would it actually take to freeze you? Wouldn't relatively small amounts of it just boil off you, taking some of your heat with it, but not actually hurting? Actually, the boiling itself would help to protect from more liquid contact, thanks to the Leidenfrost effect.

Boris' death in GoldenEye doesn't seem realistic to me. He'd have to be submerged in a bath of cryogenic liquid for probably well over ten seconds to freeze solid.

Well with a can of compressed air it would take around 5 seconds of continuous, close proximity spray to cause the organic material to freeze.

 

[Borek]

Well with a can of compressed air it would take around 5 seconds of continuous, close proximity spray to cause the organic material to freeze.

On the surface.

This is not easy to calculate. It is not very difficult to freeze sticking parts or even surface, but when it comes to objects with large volume, freezing them completely may take a long time.

 

[JaredJames]

On the surface.

This is not easy to calculate. It is not very difficult to freeze sticking parts or even surface, but when it comes to objects with large volume, freezing them completely may take a long time.

Yeah, sorry, I meant the surface and a few mm underneath. Not complete freeze. Was thinking of tissue damage to skin.

I understand they use nitrogen to flash freeze products, perhaps that would be a good place to start.

 

[quietbang]

I don't intend to actually spray living beings (though my best friend did volunteer as a guinea pig on the grounds that he's been electrocuted twice and is probably already a mutant of some kind) but rather plant materials, etc.
My concern with liquid nitrogen is the possibility of dispersion after it is sprayed, and that therefore it would be difficult to control. I'm partial to my appendages.
Would it be possible to concentrate the spray in such a way that it went in a straight line with relatively little dilution?
(Yes, I realize that that should probably be posted on the engineering forum, but humour me.)

 

[JaredJames]

I don't intend to actually spray living beings (though my best friend did volunteer as a guinea pig on the grounds that he's been electrocuted twice and is probably already a mutant of some kind) but rather plant materials, etc.
My concern with liquid nitrogen is the possibility of dispersion after it is sprayed, and that therefore it would be difficult to control. I'm partial to my appendages.
Would it be possible to concentrate the spray in such a way that it went in a straight line with relatively little dilution?
(Yes, I realize that that should probably be posted on the engineering forum, but humour me.)

Nitrogen would boil off very quickly, as would Oxygen.

It wouldn't "splash around" and endanger you.

 

[Borek]

The more you wrote, the less I like it. We won't help you hurt yourself or someone else.

Topic locked.