Sciencemadness Discussion Board - Exothermic reactions

Exothermic reactions

Yntarius - 6-12-2006 at 09:34

Hi guys
I have being looking everywhere for a mild exothermic reaction with safe-to-use and non-toxic products (that excludes acids, strong bases, hidrogen, etc) and non-impossible materials to get (where i live, magnesium is forbiden by law, for example).
Anyone has any idea what could i do? All i need to do is to boil some water.
Thanks a lot!
Ariel

Waffles - 6-12-2006 at 10:02

Quote:

Originally posted by Yntarius
Hi guys
I have being looking everywhere for a mild exothermic reaction with safe-to-use and non-toxic products (that excludes acids, strong bases, hidrogen, etc) and non-impossible materials to get (where i live, magnesium is forbiden by law, for example).
Anyone has any idea what could i do? All i need to do is to boil some water.
Thanks a lot!
Ariel

That's not exactly mild. Water has an extremely high heat capacity.
The oxidation of iron powder in the presence of activated carbon and cellulose in hand warmers would come to mind as a 'mild' exothermic reaction. The 'safest' I can think of is potassium permanganate and glycerin, since that produces certainly high enough temperatures to boil water, and while potassium permanganate is a powerful oxidizer, it isn't terribly toxic, and not in the league or chlorates or perchlorates or anything in terms of stability and reactivity. Sure will stain everything around, though.

Yntarius - 6-12-2006 at 13:42

Quote:

Originally posted by iamthewaffler
That's not exactly mild. Water has an extremely high heat capacity.
The oxidation of iron powder in the presence of activated carbon and cellulose in hand warmers would come to mind as a 'mild' exothermic reaction. The 'safest' I can think of is potassium permanganate and glycerin, since that produces certainly high enough temperatures to boil water, and while potassium permanganate is a powerful oxidizer, it isn't terribly toxic, and not in the league or chlorates or perchlorates or anything in terms of stability and reactivity. Sure will stain everything around, though.

Well i think i said it wrong. By mild, i meant it doesnt have to be very fast and explosive, but yea you are right, water takes quite some energy to boil.
Whats are the outcome from potassium permanganate and glycerin? Are those chemicals bad to be ingested? lol

Thanks again
Ariel

[Edited on 6-12-2006 by Yntarius]

mericad193724 - 6-12-2006 at 14:34

Is this for a science project of some kind?

How about a chemical reaction that generates a flammable gas which when mixed with oxygen, and burned, is VERY exothermic. If this would work for you then try aluminum foil and Sodium Hydroxide, available as drain opener crystals(Draino). Those are very easy to get. The sodium hydroxide gets hot, but not hot enough to boil water, the hydrogen however can be burned very HOT!

Edit: also, adding a concentrated strong acid such as sulfuric acid to water will cause it to get really hot, maybe even boil! This is pretty dangerous since sulfuric acid eats skin pretty well!

good luck.

Mericad

[Edited on 6-12-2006 by mericad193724]

Yntarius - 6-12-2006 at 14:54

Quote:

Originally posted by mericad193724
Is this for a science project of somekind?

How about a chemi reaction that generates a flammable gas which when mixed with oxygen, and burned, is VERY exothermic. If this would work for you then try aluminum foil and Sodium Hydroxide, available as drain opener crystals(Draino). Those are very easy to get. The sodium hydroxide gets hot, but not hot enough to boil water, the hydrogen however can be burned very HOT!

good luck.

Mericad

Not exactly a science project... hehehe
I have a college project in witch I'm suposed to find alternative ways to generate power. Since everyone uses burning coal and solar energy, i figuered to maybe try to use chemical energy to boil water and therefore spin the turbine. But since it will be an open fair, with kids and all, i wanted to be on the safe side hehehe
Isn't burning H2 VERY dangerous? heheehe

Ozone - 6-12-2006 at 16:17

Yntarius,

There are a great many good exothermic reactions, some of which are relatively safe for the unexperienced to perform.

The safest of these, that I know off-hand, was mentioned in passing by iamthewaffler. Simply take iron powder (or filings, they are very easy to get), add some brine (water saturated with NaCl, table salt), and some extra water. Let this sit for a while until a tiny amount of rust is formed (this is not required, but seems to make the next part proceed with greater velocity). To this is added peroxide (H2O2), stronger is better, but beware as even with 10% the mixture will boil--higher concentrations than this would likely be dangerous. This should work with OTC 3%, but my "expedited rust preparations" were made using 10%.

On the same tangent is the slow (dropwise) addition of dilute H2O2 to common household bleach. Here, the H2O2 is oxidized by the NaOCl (5.9% diluted 1:1) to immediately yield O2 and NaCl (some NaClO3 is also likely formed). The Resulting O2 could be used as is to spin a small turbine...or, it could be combined with H2 or some other fuel (which is risky because H2:O2 mixtures can spontanously ignite or explode if the proportions of each are not correct (bad, but fun idea!). Whew, oxyhydrogen is *really* hot.

Look up hydrogen peroxide for rocket propellent, etc. for some interesting ideas!

Good luck and be careful,

O3

guy - 6-12-2006 at 18:44

Quote:

Originally posted by Yntarius

Quote:

Haha Good luck. You'll be famous if you actually discover something like that.

Yntarius - 7-12-2006 at 07:40

Quote:

Originally posted by Ozone
Yntarius,

There are a great many good exothermic reactions, some of which are relatively safe for the unexperienced to perform.

The safest of these, that I know off-hand, was mentioned in passing by iamthewaffler. Simply take iron powder (or filings, they are very easy to get), add some brine (water saturated with NaCl, table salt), and some extra water. Let this sit for a while until a tiny amount of rust is formed (this is not required, but seems to make the next part proceed with greater velocity). To this is added peroxide (H2O2), stronger is better, but beware as even with 10% the mixture will boil--higher concentrations than this would likely be dangerous. This should work with OTC 3%, but my "expedited rust preparations" were made using 10%.

On the same tangent is the slow (dropwise) addition of dilute H2O2 to common household bleach. Here, the H2O2 is oxidized by the NaOCl (5.9% diluted 1:1) to immediately yield O2 and NaCl (some NaClO3 is also likely formed). The Resulting O2 could be used as is to spin a small turbine...or, it could be combined with H2 or some other fuel (which is risky because H2:O2 mixtures can spontanously ignite or explode if the proportions of each are not correct (bad, but fun idea!). Whew, oxyhydrogen is *really* hot.

Look up hydrogen peroxide for rocket propellent, etc. for some interesting ideas!

Good luck and be careful,

O3

Ozone, are those reactions hot enought to boil water? I remember doing some experiments with H2O2, but nothing that hot....
Anyways, its starting to become very clear to me that the best reaction to get lots of heat is oxidatting some metal, catalized with NaCl and a sacrifice metal. I think I'm going to have to do some experiments with iron, copper, aluminium and other easy-to-get metals... I really hope this works....

Quote:

Originally posted by guy
Haha Good luck. You'll be famous if you actually discover something like that.

I hope you are right guy.... I'll give the forum its credits tho

heheheh

Im open to more sugestions : )

Thanks guys!
Ariel

Ozone - 7-12-2006 at 15:21

Oh yes! The expedited oxidation of iron is quite exothermic. The bubbling is steam (the O2 is added to the iron). An excess of iron can be continuously fed peroxide solution to yield heat and steam until the Fe is totally oxidized (which appears to take quite a while).

If I have time, I'll do the rxn tomorrow and try to get a small vid to post here.

Good luck,

O3

Yntarius - 8-12-2006 at 10:04

Quote:

Originally posted by Ozone
Oh yes! The expedited oxidation of iron is quite exothermic. The bubbling is steam (the O2 is added to the iron). An excess of iron can be continuously fed peroxide solution to yield heat and steam until the Fe is totally oxidized (which appears to take quite a while).

If I have time, I'll do the rxn tomorrow and try to get a small vid to post here.

Good luck,

O3

This is awesome! lol
I didnt hit the 100C yet, but i got close to 80 using powder iron, salt and 12% peroxide! I saw a 42% peroxide bottle on the store, but i bought the 12% at least to start the tests (a lot cheaper)....
Gotta love womans product section, you find a lot of chemicals in there hahahahahah
I'll keep you guys updated, including the exact weights and proportions once it works as i want : )

And im trying to catalize this reaction with some other metals... Maybe aluminum powder (being iron its sacrifice metal and since aluminum oxides a lot faster then iron)

Thaks once more guys

Ariel

12AX7 - 8-12-2006 at 13:03

Aluminum tends to be resistant to air and water...

To work with aluminum, you'll need something like lye or acid, which dissolves the aluminum and its oxide, plus something to handle the hydrogen, perhaps MnO2 (think dry cells). But that would likely be too rapid, so zinc would be a better cadidate. In this case, you have essentially the process inside an alkaline (if using NaOH/KOH) or dry cell (using NH4Cl I believe; NaCl should also work), but assembled in such a way that it won't explode under short circuit.

Tim

Dr. Beaker - 9-12-2006 at 01:05

If you only need a power source to rotate a turbine then you don't really need to use steam for it - you just need a reaction that produces gas.
take powdered limestone (or sodium carbonate/bicarbonate) and add viniger or diluted acetic acid. do it in a pressure proof vessels and use the gas pressure to make electricity.

YT2095 - 9-12-2006 at 04:41

the easiest and probably safest exothermic reaction would be the addition of water to Calcium Oxide.
it`s the same method used in some of these ready meal heat packs.

EDIT: and if you`re wondering how to employ this, it`s really quite simple, you`ll meed a plastic macdonalbs straw, and then put in several large pin holes through it along its length, put this inside a large pyrex test tube, and then fill the tube with the calcium oxide granules, when you want to activate it, pour water inside the straw.
the water will come out of the holes you made and into the CaO.
this will start to get very hot, so put this tube in your cup of cold water and just wait

[Edited on 9-12-2006 by YT2095]

Yntarius - 9-12-2006 at 08:19

Quote:

Originally posted by 12AX7
Aluminum tends to be resistant to air and water...

To work with aluminum, you'll need something like lye or acid, which dissolves the aluminum and its oxide, plus something to handle the hydrogen, perhaps MnO2 (think dry cells). But that would likely be too rapid, so zinc would be a better cadidate. In this case, you have essentially the process inside an alkaline (if using NaOH/KOH) or dry cell (using NH4Cl I believe; NaCl should also work), but assembled in such a way that it won't explode under short circuit.

Tim

An update to you guys
I've mixed about 4 grams of powder iron, 1g of powder aluminium, about 20g of kitchen salt (with just a little water so i could make a homogene mass between the salt and the metal dust) and 100ml of peroxide (12%).... Reaction started instantly and got pretty hot very fast. It reached 100ºC within the first 30 seconds and holded the 100ºC for as long as 9 minutes, when the reaction started to slow down due to the lack of more peroxide...
Still trying to find the best balance between the materials, monday I'm buying some more peroxide (50% this time) and pure (NaCl), in order to make this a more reliable experiment. Only problem is that aluminium powder is monitored by the army, so monday i'm gonna try to find some small aluminium scraps. So far Ive made my own hehehe

Dr. Beaker, the advantage on oxiding the metal instead of using bicarbonate and viniger is that with very little metal dust i can make the reaction last very long, just have to keep adding peroxide (with the left over of the experiment described above, i just kept adding peroxide and it kept going for almost 30 min without adding any adicional metal powder)

YT2095, isnt CaO not safe to handle without gloves and all? How do the heat packs work? Do you open it to put the water inside? Sounds like an interesting reaction, I'm gonna research more on the CaO tho, see how safe it is.

This is starting to come out a lot faster then I expected, thanks for all the help guys. And keep them comming heheh

Thanks : )
Ariel

YT2095 - 10-12-2006 at 02:21

the ones I`ve seen have water on one side and CaO on the other seperated by a thin metal sheet, there`s a plastic dome with a sharp plastic bit stuck to it, you presson this dome and the sharp peice punctures the metal seperator allowing the liquid to mix with the CaO, you give it a quick shake and just leave it to stand for a few mins.
CaO is non toxic, and quite safe to handle without gloves for short periods of time, it isn`t all that caustic, just keep it dry.

get some sea shells and smash them up, then roast them in a hot fire, that`s how the CaO is made in many of the heat packs, in fact if you take one appart and start dissolving the caO in dilute HCl you`ll even see some bits that are quite clearly sea shell fragments

Ozone - 10-12-2006 at 07:34

Yntarius,

Interesting, your results are parallel to mine; Have you run a control experiment without the Al°--the exotherms plotted over time could tell you quite a bit (as will the maximum).

Simple and effective; I really like this rxn! Be careful though with the stonger peroxide--it might get a bit more frisky than intended. I would keep with the 10-20% range with continual addition, say, with a dropping funnel or the like. It should reach steady state unless 1) you run out of water, which is unlikely with the constant addition of dilute H2O2 or, 2) you run out of iron, or 3) you blow the contents out of the vessel.

I'm not too sure about the Al°. I wanted to try it the other day, but was sidetracked by a bad tooth. I'll see about it tomorrow.

CaO is nothing to worry about, the inhaled dust is irritating however, so a dust mask (nothing fancy) might be a good idea if you notice dust "poofing" everywhere.

Waiting for the darvocet to kick in,

O3

Ozone - 10-12-2006 at 12:15

Here's one...I think this would be applicable for the "water activated fire" thread found elsewhere:

Exothermic demo

John Bartmess, Charles Feigerle, George Schweitzer, Wes Fellers, Peter Smith
Department of Chemistry, University of Tennessee, Knoxville

Chemical & Engineering News (15 Jun 1998) Vol. 76, No. 24, pp. 4.

--------------------------------------------------------------------------------

We wish to point out a safety hazard with a widely performed standard chemical demonstration that caused significant damage recently in a teaching laboratory in the chemistry department at the University of Tennessee, Knoxville.

The Belousov-Zhabotinsky oscillator reaction described in Bassam Shakhashiri's" Chemical Demonstrations: A Handbook for Teachers of Chemistry," Vol. 2, involves the cerium ammonium nitrate-catalyzed redox reaction of potassium bromate with malonic acid. This reaction was carried out in an honors general chemistry laboratory without incident during the afternoon, but a fire was discovered in the lab two hours after everyone had left. It destroyed the wooden drawers beneath a stone benchtop before being extinguished by the fire department.

Investigation revealed that the three chemicals used are stable when mixed dry, and react as expected when in dilute solution. However, when 0.5 g of each are mixed together, and between one drop and 3 mL of water added, a very exothermic reaction occurs with considerable fuming. All three chemicals are needed for this to initiate. When carried out on a piece of filter paper, ignition of the paper occurred.

We suspect that in the teaching laboratory, dry chemicals were spilled during weighing, and, rather than being disposed of in the aqueous heavy-metal waste container, were placed in a trash can. This was stored under a sink with a leaky drainpipe, and the critical amount of moisture set off the reaction after everyone had left the room.

There is a safety warning in the experimental procedure regarding bromates being strong oxidizing agents and indicating that mixtures with finely divided organic materials are easily ignited. The catalytic nature of the cerium salt on this is not indicated, however. We alert people to the hazardous nature of this particular mixture, under conditions that are not unusual.

Return to List of Safety Letters
Return to Chemical & Engineering News Home Page

--------------------------------------------------------------------------------

This page last revised December 7, 1998
© Copyright 1998 by the American Chemical Society

Interesting!

O3

darkurza - 4-1-2007 at 07:33

Calcium Chloride + Water should give a small exothermic reaction. I believe CaCl2 is road salt.

Maya - 4-1-2007 at 11:17

Calcium Chloride + Water should give a small exothermic reaction. I believe CaCl2 is road salt.>>>>>>>

No, that is an ENDOTHERMIC rxn which is less heat = more cold,

EXOTHERMIC is the opposite

UnintentionalChaos - 4-1-2007 at 11:27

Actually, dissolving CaCl2 is exothermic. Try it out. It's part of the reason it's sold as ice-melt for driveways. I remember reading that making a saturated solution can bring the temperature up to about 54C (not near boiling, but unexpectedly hot). Ammonium Nitrate will give you the dead opposite. Sold as instant, one-use ice packs.

[Edited on 1-4-07 by UnintentionalChaos]

Aqua_Fortis_100% - 4-1-2007 at 20:29

Quote:

originally posted by Ozone:
On the same tangent is the slow (dropwise) addition of dilute H2O2 to common household bleach. Here, the H2O2 is oxidized by the NaOCl (5.9% diluted 1:1) to immediately yield O2 and NaCl (some NaClO3 is also likely formed). The Resulting O2 could be used as is to spin a small turbine...or, it could be combined with H2 or some other fuel (which is risky because H2:O2 mixtures can spontanously ignite or explode if the proportions of each are not correct (bad, but fun idea!). Whew, oxyhydrogen is *really* hot.

VERY CARE when handling H2O2,specially conc. solutions...is just a very tracherous thing...
e.g. the reaction with conc. Na2S solution still was more violent..just thrown off almost making a mini boom and falling in my right eye..just when i not using goggles...then i washed quickly with TONS of water.. BAH! lucky i'm not blind...
another hot (but bad )thing is put a pinch of MnO2 from dry cell baterries (or KMnO4) in some mls of conc. H2O2(i used 20ml of 50%) ...is REALLY a good thing if you use the goggles.. and keep distance.. the bottle with the stuff instantly turns very hot and the Black H2O2 decomposing foams may even to overflow of big bottles...
one time i (remotelly) put some alcohol in the conc. H2O2 and throw a lighted match in it..instantly throw also the MnO2 pinch.. run to behind of my "shield" and observed (with goggles).. at the start ,isn't much violent but it's will be turns more and more violent after each second which pass... small explosions.. and finishes in a more violent BOOM....i think which O2 released from H2O2 decomposing turns alcohol burns MUCH more violent..even with explosions...

so again Yntarius, VERY , GREAT CARE when handling with H2O2..remember which its can also forms a "exothermic reaction" with your skin, "burning" them with a white stain...

[Editado em 5-1-2007 por Aqua_Fortis_100%]

Ozone - 4-1-2007 at 20:45

Try (NH4)6Mo7O24. This is the catalyst** used (in conjunction with a trap-H2SO4 and KI) for the titrimetric assay vs. Na2S2O3.

MnO2 is fantastic (in terms of kinetics--this has to do with multiple (and high) oxidation states).

Fe3+ works, but sucks (Fenton, I know, but quite slow, by comparison, on a mol/mol basis).

As for safety, just don't tempt Lord Darwin. Wear gloves and safety glasses--at the very least 30-50% will instantly turn skin into ashy, white leather (and catch some things on fire...

).

Reasonable dilution, good safety practice, slow addition, and *yark* common sense is key when handling strong H2O2.

Have fun, be safe (2 eyes, 10 fingers = good),

O3

[Edit] ** nevermind blood, with both the Fe and catalase (where's Chemoleo? I can go through this, but I fathom that the Biochemist might paint a more colorful and informative picture...).

[Edited on 5-1-2007 by Ozone]

Aqua_Fortis_100% - 4-1-2007 at 20:59

Quote:

(NH4)6Mo7O24

is a tipical thing which i wish keep distance ehehe...

Ozone, what the MOST tracherous and hazardous exothermic reaction which you made???
now i'm curious..

Ozone - 4-1-2007 at 21:19

Quote:

Originally posted by Aqua_Fortis_100%

Quote:

(NH4)6Mo7O24

is a tipical thing which i wish keep distance ehehe...

Ozone, what the MOST tracherous and hazardous exothermic reaction which you made???
now i'm curious..

It is really quite stable--It is a solution of ammonium molybdate made with NH3OH and water. It can be kept in very concentrated form (if refrigerated without air or light). It *is* a very efficient catalyst for decomposing H2O2, however.

As for the most exothermic reaction I've done/seen..that requires some thought as I have seen a few good ones. the first that comes to mind is 2,4-sec-butyl-dinitrophenol and concentrated sulfuric acid. The best part is the "quiet" induction period before the exotherm...

Sniff with care, my friend,

O3

Aqua_Fortis_100% - 4-1-2007 at 22:21

Thanks Ozone...
when in (VERY near) future , i try this in High school. home lab should be a good thing to try reactions of this type..
this "2,4-sec-butyl-dinitrophenol" seems to me as a explosive and poisoning material, because of "dinitrophenol" termination... i will search this..

[Editado em 5-1-2007 por Aqua_Fortis_100%]

[Editado em 5-1-2007 por Aqua_Fortis_100%]

Maya - 5-1-2007 at 03:41

<<Actually, dissolving CaCl2 is exothermic. Try it out. It's part of the reason it's sold as ice-melt for driveways. I remember reading that making a saturated solution can bring the temperature up to about 54C (not near boiling, but unexpectedly hot). Ammonium Nitrate will give you the dead opposite. Sold as instant, one-use ice packs.>>

UC, you are wrong . CaCl2 does not melt ice because of exothermic rxn . It melts ice b/c it lowers the freezing point of the solution as it dissolves which actually COOLS the ice even further

! But the freezing point goes down even further the more it dissolves.

That is the principle behind determining Molar Mass by Freezing Point Depression. Basic 1st year chemistry.

http://chemistry.about.com/cs/howthingswork/a/aa120703a.htm

encipher - 5-1-2007 at 09:24

Maya,

What UC said was technically correct. The dissolving of CaCl2 in H2O is an exothermic reaction, which releases heat. He also did state that it was only part of the reason the ice melts. You were incorrect in saying that the dissolving of CaCl2 actually cools the ice even further. Freezing point depression has nothing to do with how cold or hot the solution gets when a salt is dissolved, it has to do with the temperature at which the solution freezes (which is lowered) or boils(which is raised).

darkurza - 5-1-2007 at 10:26

Quote:

Originally posted by Maya
<<Actually, dissolving CaCl2 is exothermic. Try it out. It's part of the reason it's sold as ice-melt for driveways. I remember reading that making a saturated solution can bring the temperature up to about 54C (not near boiling, but unexpectedly hot). Ammonium Nitrate will give you the dead opposite. Sold as instant, one-use ice packs.>>

UC, you are wrong . CaCl2 does not melt ice because of exothermic rxn . It melts ice b/c it lowers the freezing point of the solution as it dissolves which actually COOLS the ice even further

Maybe Calcium Chloride isn't road salt. But in Wiki, it says

'Calcium chloride reacts exothermically with water and can burn the mouth and esophagus.'

UnintentionalChaos - 5-1-2007 at 11:10

I never said anything about a reaction because no reaction is occuring. The calcium chloride is dissolving in water, BUT it first goes from anhydrous (or dihydrate or tetrahydrate depending on how well you sealed the container) to hexahydrate, the bond forming process of which IS quite exothermic. I am fully aware of feezing point depression, thank you very much.

Obviously, freezing point depression is why it keeps the ice melted later on, but gram for gram (and cm^3 for cm^3), you actually get more ions (and thus a low freezing point) from normal NaCl. So why use CaCL2? First of all, you get the inital exothermic hexahydrate formation, quickly allowing the ice to melt and the salt to disperse into solution. Second, CaCl2 is about twice as soluble in water as NaCl (at least at 20C, so I would imagine it is still somewhat more soluble at 0) so you can, for a given mass of ice, lower the freezing point more (assuming you have all the CaCl2 you need) than you could with NaCL. Thirdly (and don't quote me on this one), the calcium should be less harmful to plants than sodium and for anyone who is a gardener or is a bit neurotic about their lawn, that claim makes all the difference in the world. Plus, It's sale as de-icer makes for cheap and abundant dessicator material as well as a useful chemical.

Oh, and thanks for the support encipher, but the actual bond-breaking of dissolution (or melting, vaporization, etc.) is endothermic and will cool the brine back down again. Try this with a salt that doesn't form hydrates first such as the very dramatic ammonium nitrate.

[Edited on 1-5-07 by UnintentionalChaos]

Maya - 5-1-2007 at 11:28

the de icer they use on planes and on roads is the hydrated form, I'm pretty positive about this.

If you are working with the anhydrous salt of course you are going to get heat from the formation of water of hydration, but I think what was intended ( as I assumed ) was the use of the fully hydrated form.

Drop that into a bucket of ice at 0 deg then mix and stick a thermometer in there and I'll wager a thousand plantains that your temp drops like a rock

[Edited on 5-1-2007 by Maya]

UnintentionalChaos - 5-1-2007 at 11:48

I figure if it's sold as "heat-melt" and touted as getting hot as it dissolves, it cant possibly be hexahydrate. Maybe the salt you're used to is the hexahydrate for the sole purpose of being highly soluble in water, probbaly much easier to store, and (maybe) less environmentally hazardous.

1000 plantains, eh? I wouldn't bet 244g of zinc and 6g of copper on that one ($1 US in post-1982 pennies

) I'm not trying to argue with basic scientific principles. That would be daft (although if you are actually on to something, you might just be the next einstein)

science fair

mamakat - 17-1-2007 at 17:29

hi my daughter and I are working on a science fair project and we want to make a heat pack that can be portable to use in emergency kits to boil water. however we are going to be working in the kitchen and she is 11. I'm really concerned that the rest of the family might be upset if we blow up the kitchen any very safe suggestions.

Ozone - 17-1-2007 at 18:43

mamakat,

Check out the very reaction you are looking for (page one, this thread), which Yntarius has made to work. It consists of:

1) iron powder or filings (steel is OK)
2) table salt (sodium chloride)
3) water
4) hydrogen peroxide (for this level of experiment over-the-counter (OTC) 3% is probably OK).

As I mentioned much earlier in the tread (and have been lazy to deliver) I will film this reaction tomorrow and post it so that is can be more easily reproduced. This reaction is quite safe and easy to do (it is also a wonderful example of reduction/oxidation (REDOX) chemistry) We will just have it get warm not boil water

.

Best wishes,

O3

[Edited on 18-1-2007 by Ozone]

Whoosh

franklyn - 18-1-2007 at 08:54

Curious how the original proposition from the middle of last year by ' Yntarius '
enquiring about an improvised power source for a prime mover has become a
rant about melting ice

The notion of chemically boiling water for steam to drive a turbine is so
horrendously inefficient that it hurts my sensibilities merely contemplating such
a scheme.

An open Rankine cycle which is what this is known as in thermodynamics has to
operate at high temperature to produce useful power. Utility scale powerplants
operate with 400 degee steam. One would be lucky to obtain measurable torque
from the vapor of merely boiling water.

Actually 'Dr Beaker' had the right notion

Quote:

Originally posted by Dr. Beaker
If you only need a power source to rotate a turbine then you don't really need
to use steam for it - you just need a reaction that produces gas.
Take powdered limestone (or sodium carbonate/bicarbonate) and add viniger or
diluted acetic acid. do it in a pressure proof vessels and use the gas pressure
to make electricity.

but the wrong application.

To most efficiently couple the output one should use the pressure produced by
a confined gas producing reaction to act on a sealed liquid reservior and use
the high pressure fluid to drive a reversible positive displacement liquid pump to
drive a generator. This will produce arbitrarily high torque to the design limits of
the pump, for as long as the reservoir can supply fluid.

If a portable scheme is imagined one can envision a scheme whereby the
working fluid is captured in another empty reaction vesel to be subsequently
expelled back again into the first container in alternating cycles by a gas
generator delivering power sufficient to drive the vehicle. A similar mechanism
has been built and operated using liquid air as the gas source although it
used this directly to act on the pistons.

I am reminded of a proposed submarine that would porpoise diving at an angle
to the depth of 3000 feet where smokeless gun propellant would ignite to
purge the ballast tanks and the now bouyant submarine would rise at a angle
to the surface to repeat this process.

.