Endothermic reaction

[walsh]

Are there any compounds readily available which can create an endothermic reaction when combined with water, without being deconstruct-able to an explosive.

I have had an idea, but my initial plan won't work, as if probably be arrested trying to buy ammonia nitrate.... Unless it's possible to make it inert, whilst retailing the endothermic quality.

Would help if the solution was non-toxic also...

I'm stuck. Thanks in advance.

[Moonhawk]

Caustic soda pearls are highly exothermic when dissolved in water (the water will actually boil around them if you use enough) - available from many hardware stores as a drain cleaner.

The resulting solution is pretty nasty though (highly alkaline).

[weeboot]

Moonhawk said:

Caustic soda pearls are highly exothermic when dissolved in water (the water will actually boil around them if you use enough) - available from many hardware stores as a drain cleaner.

The resulting solution is pretty nasty though (highly alkaline).

OP requires ENDO not EXO

[battered]

walsh said:

Are there any compounds readily available which can create an endothermic reaction when combined with water, without being deconstruct-able to an explosive.

I have had an idea, but my initial plan won't work, as if probably be arrested trying to buy ammonia nitrate.... Unless it's possible to make it inert, whilst retailing the endothermic quality.

Would help if the solution was non-toxic also...

I'm stuck. Thanks in advance.

Table salt and ice. Not endothermic as such but exploits the d-H fusion of ice to absorb the energy from the fluid.

The practicality: Take half a bucket of water. Add half a bucket of ice. Temperature 0°C. Add 1kg salt, stir. Temperature -5, maybe even -10 with enough salt.

[Nimby]

battered said:

Table salt and ice. Not endothermic as such but exploits the d-H fusion of ice to absorb the energy from the fluid.

The practicality: Take half a bucket of water. Add half a bucket of ice. Temperature 0°C. Add 1kg salt, stir. Temperature -5, maybe even -10 with enough salt.

You're not actually "making" cold. That just allows brine to approach the temperature of the ice cubes (say -18C if straight out the freezer) without the liquid phase freezing.

I don't think adding sodium chloride to water (both at room temperature) cools it, though ammonium chloride would.

[battered]

Nimby said:

battered said:

Table salt and ice. Not endothermic as such but exploits the d-H fusion of ice to absorb the energy from the fluid.

The practicality: Take half a bucket of water. Add half a bucket of ice. Temperature 0°C. Add 1kg salt, stir. Temperature -5, maybe even -10 with enough salt.

You're not actually "making" cold. That just allows brine to approach the temperature of the ice cubes (say -18C if straight out the freezer) without the liquid phase freezing.

I don't think adding sodium chloride to water (both at room temperature) cools it, though ammonium chloride would.

I didn't say that you were. That's why I said "Not endothermic as such but exploits the d-H fusion of ice to absorb the energy from the fluid."

You also said "That just allows brine to approach the temperature of the ice cubes (say -18C if straight out the freezer) without the liquid phase freezing." and that's not true. What you are actually doing is using the salt to accelerate the rate of thawing of ice. This requires energy, in the form of latent heat of fusion, and it has to suck this energy from the fluid, so cooling it. Hence the delta-H fusion comments earlier. The phase change generates energy going one way and consumes it going the other, just like evaporative cooling.

[Nimby]

Yes I agree, though the ice would melt even without salt and cool the water to 0C, but no lower, both due to its low temperature and latent heat. I was pointing out that the reason you can measure -5 or -10 is because the water doesn't freeze at 0C when salt (or indeed anything) is dissolved in it.
However if you put ice cubes at -18 into cold water I suspect that at first you'd get more ice formed (releasing latent heat) - there would be quite a complicated dynamic equilibrium depending on the concentration and size of the ice cubes, conductivity of ice, convection etc.

Damn physics - this is why I studied chemistry!

[Moonhawk]

weeboot said:

Moonhawk said:

Caustic soda pearls are highly exothermic when dissolved in water (the water will actually boil around them if you use enough) - available from many hardware stores as a drain cleaner.

The resulting solution is pretty nasty though (highly alkaline).

OP requires ENDO not EXO

Oops - sorry

[V8LM]

Urea dissolving is water is the commonly used practical demonstration, and used in cooling packs.

[walsh]

Thanks for the help guys.

A little background for application.

I had an idea whilst a little sozzled ( as you do, proper back of a napkin stuff), for a chemical, portable drinks cooler. My idea was around a disposable powder capsule/ Gel Maybe, which could be combined with another to create an endothermic solution. Made a million times easier for application if the other compound happens to be water.

I have no interest in becoming the chief munitions officer of my local nick however.

Salt wont do what i need it to as far as i am aware, urea may do the trick, but...well, no one wants to piss on their beer cans now do they.

Any other suggestions. Or.. any derivative compounds ( Some sort of stabilizing agent to remove the denotation aspect, if that's even possible? of ammonia nitrate which could be used for this purpose?

Thanks again, as you can probably guess, I am not exactly a scientist!

[battered]

Already exists as described above. Urea based cooling packs. You regenerate them after use by soaking the sealed pack in boiling water. To use them you bash them and they start crystallising and get cold. You chuck them in an ice bucket and add water and a bottle.

[schmunk]

Wrap one of these around your drink: https://www.koolpak.co.uk/Hot-Cold-Therapy/Instant...

[battered]

Been thinking about this one a bit, in response to these thoughts:

"Yes I agree, though the ice would melt even without salt and cool the water to 0C, but no lower, both due to its low temperature and latent heat. I was pointing out that the reason you can measure -5 or -10 is because the water doesn't freeze at 0C when salt (or indeed anything) is dissolved in it.
However if you put ice cubes at -18 into cold water I suspect that at first you'd get more ice formed (releasing latent heat) - there would be quite a complicated dynamic equilibrium depending on the concentration and size of the ice cubes, conductivity of ice, convection etc.

Damn physics - this is why I studied chemistry!"

It's not actually complex at all. If you put ice cubes at -18C into water then the mixture would very quickly stabilise at 0C. It would form a dynamic equilibrium of sorts (is there any other kind?) but it would stabilise as "ice+water@0C" until it all either thawed or froze, depending upon ambient temperature. This holds for all values of ice plus water with the exception of ridiculous extremes. Basically in any case where you have liquid water and solid ice in a mixture the mixture will very quickly stabilise at 0C. Salt will lower this at the expense of more rapid melting, but this has nothing to do with the start temperature of the ice. A bucket of ice at 0 plus a bucket of water at +1 will go to zero, add salt and it will go well below zero as the melting of the ice sucks energy out of the system.

You're right about physics though, bloody counterintuitive at times.

[motco]

Nimby said:

You're not actually "making" cold. That just allows brine to approach the temperature of the ice cubes (say -18C if straight out the freezer) without the liquid phase freezing.

I don't think adding sodium chloride to water (both at room temperature) cools it, though ammonium chloride would.

I seem to remember asking this question when I worked in lab and ammonium chloride was the best I could find easily.

[Monty Python]

http://chemistry.about.com/od/lecturenotesl3/a/end...

[jimmy156]

Sodium thiosulphate reacts endothermically when put into water... No idea how easy it is to get hold of.

[otolith]

jimmy156 said:

Sodium thiosulphate reacts endothermically when put into water... No idea how easy it is to get hold of.

Very easily. It's used by people who develop their own photographs, and also as a dechlorinator.

Quick Google;

https://apcpure.com/product/Sodium_Thiosulphate_Pe...