# Exothermic Reactions



## Potty (Dec 23, 2012)

I need to know if there is a combination of chemicals that would cause a reaction which would generate enough heat to warm a small area... the size of a tent for instance. 

Idealy one of the ingredients needs to be a rock, I know there are some rocks that react in certain ways when acid is poured onto them. The second ingredient needs to be transportable in a vial or jar that can be kept about ones person. The other requirement is that any gasses that are given off as a result of the reaction isn't deadly.

So, is Edward Elric out there?


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## Lewdog (Dec 23, 2012)

I'm guessing a rock with Magnesium?  Done!  The hard part will be finding the a vial to hold water...

Magnesium Oxide & Water Reaction | eHow.com


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## Potty (Dec 23, 2012)

And it needs to last longer than a few seconds... I'm trying for a chemsists take on a camp fire.

Edit: It's a fantasy so we can use a little artistic lisence, but I want to avoid "Mystery rock number one reacts well with mystery liquid number two" as much as possible.


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## Lewdog (Dec 23, 2012)

Potty said:


> And it needs to last longer than a few seconds... I'm trying for a chemsists take on a camp fire.



It says it is highly exothermic...man you are picky.  

I looked up what chemicals are used to produce heat in Hand packs and MRE heating packs and it is the same thing as what I already listed.  :/


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## Potty (Dec 23, 2012)

Hmmm... I seem to remeber from chemistry lessons that magnezium and water produces very fast reactions... to the point of being almost explosive. Perhaps I'm thinking of something else. So I take it Magnezium can be gathered from rocks? or is it a rock? The idea being that they can gather the rocks into a pile, pour the liquid ontop and get a reaction. I think I'm going to have to "Coz it's magic" it aren't I?


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## Lewdog (Dec 23, 2012)

Potty said:


> Hmmm... I seem to remeber from chemistry lessons that magnezium and water produces very fast reactions... to the point of being almost explosive. Perhaps I'm thinking of something else. So I take it Magnezium can be gathered from rocks? or is it a rock? The idea being that they can gather the rocks into a pile, pour the liquid ontop and get a reaction. I think I'm going to have to "Coz it's magic" it aren't I?



Magnesium oxide is a powder found in rocks.


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## Potty (Dec 23, 2012)

Thanks Lewdog  I appreciate your help.


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## Lewdog (Dec 23, 2012)

No problem, it's been like 19 years since my last Chemistry class.  I feel like I didn't something important today, and I helped you out too.


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## the antithesis (Dec 23, 2012)

Potty said:


> I think I'm going to have to "Coz it's magic" it aren't I?



Probably, yeah. If such a thing were possible, they'd be selling them in camping stores.

I found this page where they go over the MRE and that page deals specifically with the chemical heater. The article explains that rusting iron causes heat, but it's so slow that you don't really notice. So you may be right that magnesium oxidizes instantly, but that's why it's useful as a chemical heater while iron is too slow to work.

To make your chemical heater a little more plausible, it should be a binary system. A chemical reaction generates a mess of heat and a second portion is a dense material that absorbs that heat and then slowly doses it out over time. I guess this is how fireplace hearths would heat a home. People would light a fire and they could let it die out and the heat absorbed by the brickwork would continue to heat the home for a while, hours if it was large enough. You could have your character camp on a rock and then use a tool that fires a spike into the rock and inserts a chemical heater which then heats the rock and the group can enjoy the radiant heat. Just an idea. Or you could use a phaser to heat the rocks like Chekov once did.


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## Lewdog (Dec 23, 2012)

the antithesis said:


> Probably, yeah. If such a thing were possible, they'd be selling them in camping stores.
> 
> I found this page where they go over the MRE and that page deals specifically with the chemical heater. The article explains that rusting iron causes heat, but it's so slow that you don't really notice. So you may be right that magnesium oxidizes instantly, but that's why it's useful as a chemical heater while iron is too slow to work.
> 
> To make your chemical heater a little more plausible, it should be a binary system. A chemical reaction generates a mess of heat and a second portion is a dense material that absorbs that heat and then slowly doses it out over time. I guess this is how fireplace hearths would heat a home. People would light a fire and they could let it die out and the heat absorbed by the brickwork would continue to heat the home for a while, hours if it was large enough. You could have your character camp on a rock and then use a tool that fires a spike into the rock and inserts a chemical heater which then heats the rock and the group can enjoy the radiant heat. Just an idea. Or you could use a phaser to heat the rocks like Chekov once did.



So you are saying kind of like a sauna?  Have the Magnesium reaction heat water that then heats the rocks in the water?  That would create humidity and heat which would make the heat seem even hotter.  So more like placing magnesium oxide laced rocks into the water instead of vice versa.


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## Potty (Dec 23, 2012)

the antithesis said:


> Or you could use a phaser to heat the rocks like Chekov once did.



Ha!

I suppose I could have two vials of liquid that are poured over the rock together and, as you say, let the rock absorb the heat.


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## Lewdog (Dec 23, 2012)

Potty said:


> Ha!
> 
> I suppose I could have two vials of liquid that are poured over the rock together and, as you say, let the rock absorb the heat.



But if you used rocks laced with Magnesium oxide, you would already have rocks and not have to introduce new ones.

The best would be to use lava rock that is porous and would absorb and hold the heat best.  There are lots of ways you can go with this.


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## the antithesis (Dec 23, 2012)

Potty said:


> I'm trying for a chemsists take on a camp fire.



And not to be pedantic, even though I am, a regular campfire is pure chemistry. It's using the same oxidation process as magnesium, just it does it so fast it burns with a flame.

An option I'm just going to throw out there is a woodgas stove that supposedly burns more efficiently because instead of letting the wood gases scape as smoke, it burns them producing a more efficient, smokeless fire. Do-it-yourselfers can make one out of old cans. Even simpler, but likely too lo-tech for what you're trying to do is the dakota fire hole that was used by native American tribes, such as the Lakota, I believe. Two holes are dug close to each other. About a foot deep and a foot apart or so. The two holes are connected by a tunnel at their bottoms and a fire is built in one of them. As the smoke and hot gases rises out of the hole, it draws in air from the one place it can, the other hole through the tunnel. This suction action stokes the fire and causes it to burn hotter and without smoke. Both of these methods do need to be ventilated as carbon monoxide is still produced. It's a silent killer, like my cousin. This may be getting too far away what you're trying to do, but I had been told that a tea light can be sufficient heat to keep you alive if you're stranded in your car. Just kind of spitballing some ideas and alternatives which are interesting tidbits to hold for later use if not for this piece.


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## Lewdog (Dec 23, 2012)

the antithesis said:


> And not to be pedantic, even though I am, a regular campfire is pure chemistry. It's using the same oxidation process as magnesium, just it does it so fast it burns with a flame.
> 
> An option I'm just going to throw out there is a woodgas stove that supposedly burns more efficiently because instead of letting the wood gases scape as smoke, it burns them producing a more efficient, smokeless fire. Do-it-yourselfers can make one out of old cans. Even simpler, but likely too lo-tech for what you're trying to do is the dakota fire hole that was used by native American tribes, such as the Lakota, I believe. Two holes are dug close to each other. About a foot deep and a foot apart or so. The two holes are connected by a tunnel at their bottoms and a fire is built in one of them. As the smoke and hot gases rises out of the hole, it draws in air from the one place it can, the other hole through the tunnel. This suction action stokes the fire and causes it to burn hotter and without smoke. Both of these methods do need to be ventilated as carbon monoxide is still produced. It's a silent killer, like my cousin. This may be getting too far away what you're trying to do, but I had been told that a tea light can be sufficient heat to keep you alive if you're stranded in your car. Just kind of spitballing some ideas and alternatives which are interesting tidbits to hold for later use if not for this piece.



I'm thinking that there is something you are missing here.  I believe Potty wants to make the heat source builder look like a magician and not like some Joe schmo rubbing two sticks together.  I mean this isn't "Broke Back Mountain."  Ha!  No really, also by doing it this way, the tent doesn't get smokey from the fire and they die of smoke inhalation or look goofy with black stuff running out of their noses in the morning.


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## the antithesis (Dec 23, 2012)

Lewdog said:


> I'm thinking that there is something you are missing here.  I believe Potty wants to make the heat source builder look like a magician and not like some Joe schmo rubbing two sticks together.



I know. I was just throwing out other options if the magic chemical thing doesn't work. It could work if the character is established as super scientific and then uses a method that's thousands of years old. That's a juxtaposition. Or if not, it could be used in another story later. Either way.


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## Lewdog (Dec 23, 2012)

the antithesis said:


> I know. I was just throwing out other options if the magic chemical thing doesn't work. It could work if the character is established as super scientific and then uses a method that's thousands of years old. That's a juxtaposition. Or if not, it could be used in another story later. Either way.



Ash already did all this in "Army of Darkness."


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## Bloggsworth (Dec 24, 2012)

Lewdog said:


> I'm guessing a rock with Magnesium?  Done!  The hard part will be finding the a vial to hold water...



Magnesium oxide is metallic, it is not "metal" per se, come to think of it, neither is it a rock, though it is extracted from rock as it is not found as a free element in either rock or seawater. For a rapid reaction with magnesium you would need salt water as its reaction to ordinary water is at about the same rate as rust forming on ferrous metals.

Rock-wise you could use lime, which would produce heat and calcium hydroxide - Though I would fear for the lives of those inside the tent as they would probably suffocate in the fumes.

Any exothermic reaction, unless contained, will likely produce toxic fumes. Check out the chemistry involved in self-heating food & drink cans, this will give you something to work from.


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## Lewdog (Dec 24, 2012)

Bloggsworth said:


> Magnesium oxide is metallic, it is not "metal" per se, come to think of it, neither is it a rock, though it is extracted from rock as it is not found as a free element in either rock or seawater. For a rapid reaction with magnesium you would need salt water as its reaction to ordinary water is at about the same rate as rust forming on ferrous metals.
> 
> Rock-wise you could use lime, which would produce heat and calcium hydroxide - Though I would fear for the lives of those inside the tent as they would probably suffocate in the fumes.
> 
> Any exothermic reaction, unless contained, will likely produce toxic fumes. Check out the chemistry involved in self-heating food & drink cans, this will give you something to work from.



That's what is used in self heating MRE packs...Magnesium oxide and water.  That's what I said earlier...everyone wants to doubt me.  >.<



> [h=2]Precautions[/h] Magnesium oxide is easily made by burning magnesium ribbon which oxidizes in a bright white light, resulting in a powder.  However, the bright flame is very hard to extinguish and it emits a  harmful intensity of UV light. Inhalation of magnesium oxide fumes can  cause metal fume fever.[SUP][13][/SUP]



Yes your best bet to find naturally occuring Magnesium oxide is in limestone near salt water.  Do you really need all that explanation for your magician to make a poof and some heat?


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## Potty (Dec 24, 2012)

They aren't magicians... its a long story but the best example I can give is a technomage... though this is still rather inaccurate.


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## Lewdog (Dec 24, 2012)

Potty said:


> They aren't magicians... its a long story but the best example I can give is a technomage... though this is still rather inaccurate.



Technomage?  Is that like the first metallurgist and alchemist who worked to discover chemical reactions and invent things like gun powder?

If you want the absolute easiest way to get Magnesium oxide, you could send your mages to GNC and purchase Magnesium oxide capsules and break them apart for the powder inside.  $8.99 isn't a bad price on those.

http://www.gnc.com/product/index.jsp?productId=2133413


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## dolphinlee (Dec 29, 2012)

I just want to clear a few things up.  

Magnesium would sit in water all day and nothing would happen.

Magnesium metal burns brightly. You may remember taking a small piece ofmagnesium ribbon and holding it in a bunsen burner flame. The magnesium ignites and burns so brightly it hurts your eyes. Magnesium powder is used in fireworks.

Magnesium burns to form magnesium oxide. 

Now magnesium oxide does occur in nature, however, it occurs mixed with other minerals. This dilutes the magnesium oxide and stabalises it. Imagine pure magnesium oxide rock lying on the top of the ground. The smallest bit of rain would make it react to form the hydroxide. This is the reaction that gives off heat. 

Re technomage - the last one I came across was Galen in Crusade. From what I can remember he was able to use and control energy. This included gathering energy from his surroundings and focusing it into his staff.    

So this is really a dead end.

Assuming there is a mineral (X) that would react to give off useable heat. It would have to be found in its pure form to be useful. Thus it must not react with water, but it could react with acid. 

This is where accuracy problems start. Let's say we have a cricket ball sized lump of pure X. In order to release the energy as heat we have to add an acid. However the acid quickly gets used up. We'd probably have to use a bucket full of acid to react with the lump of X, and the temperature in the tent would probably go up 1°. 

There are of course really exciting exothermic reactions like the thermite reaction. Unfortunately the reaction is so fast it's classified as explosive.


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## Abdul-fattah (Jan 1, 2013)

Perhaps as a compromise, he could use chemistry to get the initial spark to start a fire, but use seomthing else to burn? As Dolphin hinted, either your reaction will be to slow for a noticable change in temperature, or it will be to fast, and destructive. I don't think there's a middle way; other then the classical fire of course. In order to slowly burn a stone you'd need temperatures which are waaaaaay beyond bonfire =)


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## dolphinlee (Jan 7, 2013)

Potty, 

When matter is taken to temperature near absolute zero they collapse as they lose the energy that bonds the particles together. 

Alternatively this can be viewed as take the energy out of matter to use for something else and leaving behind a pile of 'dust.'

Could your character take the energy out of a big rock for heating leaving behind 'dust'?


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## words (Jan 7, 2013)

The OP might consider calcium chloride and related reactions - some of which can heat water but in the main  not explosive.

The problem with exotherms is finding one that is both benign and safe. The reaction for example that produces brake disk pad  resin is EXTREMELY exothermic, from phenol (white crystalline) and derivatives of formaldehyde: but controlling some of those reactions is tough, and the products and by products are not at all pleasant. 

Exotherms are generally not "open loop" stable, because the effect of the exotherm is to create heat, the effect of the heat increases temperature, the effect of the temperature exponentially increases reaction speed which is why exotherms are often explosive which is generally true, unless done in a heat absorber, such as water to soak up heat and moderate speed.

So chemical plants that use try to stabilize these reactions in order to use them have serious control issues.


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## Bloggsworth (Jan 7, 2013)

While on the subject of exothermic reactions:

The following is reputedly an actual question given on a University of Washington chemistry final exam:

"Is Hell exothermic (gives off heat) or endothermic (absorbs heat)? Support your answer with a proof."

Most of the students wrote proofs of their beliefs using Boyle's Law (gas cools off when it expands and heats up when it is compressed) or some variant.
One student, however, wrote the following:

"First, we need to know how the mass of Hell is changing in time. So, we need to know the rate that souls are moving into Hell and the rate they are leaving. I think that we can safely assume that once a soul gets to Hell, it will not leave. Therefore, no souls are leaving.
As for how many souls are entering Hell, let's look at the different religions that exist in the world today. Some of these religions state that if you are not a member of their religion, you will go to Hell. Since there are more than one of these religions and since people do not belong to more than one religion, we can project that all people and all souls go to Hell. With birth and death rates as they are, we can expect the number of souls in Hell to increase exponentially.
Now, we look at the rate of change of the volume in Hell because Boyle's Law states that in order for the temperature and pressure in Hell to stay the same, the volume of Hell has to expand as souls are added.
This gives us two possibilities:

1 - If Hell is expanding at a slower rate than the rate at which souls enter Hell, then the temperature and pressure in Hell will increase until all Hell breaks loose.
2 - Of course, if Hell is expanding at a rate faster than the increase of souls in Hell, then the temperature and pressure will drop until Hell freezes over.

So which is it?

If we accept the postulate given to me by Ms. Therese Banyan during my Freshman year "That it will be a cold night in Hell before I sleep with you," and take into account the fact that I still have not succeeded in having sexual relations with her, then, #2 cannot be true, and thus I am sure that Hell is exothermic."

The student got the only A.


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