[chad]

I’m not very well versed in chemistry and google has been of little help, so I’m asking here. I’m looking for a couple of safe chemicals which combine to react (or dissolve etc.) endothermically. It doesn’t have to be an impressive reaction, it just has to be safe and not produce masses of gas (so that’s carbonate/ bicarbonate and acid out the window). I would preferably like neither substance to be water.

If you know of any such chemicals (if they even exist), I would appreciate your help. Thanks 

[Schrödinger]

The formation of NH₄Cl from NH₃(aq) and HCl is endothermic, I believe.

[Arkcon]

Dissolving ammonium nitrate in water is a favorite endothermic reaction for those instant cold packs.  There are others on Wikipedia, but if you need lots of cold, the endothermic reaction of ice to water remains a perennial favorite.

[Dan]

The formation of NH₄Cl from NH₃(aq) and HCl is endothermic, I believe.

I'm pretty sure it's exothermic.

Enthalpy of formation (kJ/mol):
NH₄Cl(aq): -300
HCl(aq): -176
NH₃: -81

So we're looking at -43 kJ/mol.

My source is wikipedia though, so it might be wrong.

Also, I would not really call ammonia and HCl as "safe chemicals", with reasonably concentrated solutions there is plenty of scope for permanent disfigurement. Dissolving ammonium chloride is definitely endothermic, and you'd have to do something quite spectacular to hurt yourself with it.

Also, dissolving potassium sodium tartrate (Rochelle's salt) in water is endothermic. I don't have a value to compare to ammonium chloride though.

[chad]

Thanks for your input  . I don't think I'll be able to find an appropriate reaction so will likely settle for dissolving something. I'm wary of using HCL, ammonia or a nitrate so I'll stick to looking further into the salts. Thanks again.

[Caustikola]

There's nothing to be wary of using NH4Cl. Just follow safety precautions

[408]

And ammonium nitrate is harmless.  Just don't eat it.

[Enthalpy]

And ammonium nitrate is harmless.  Just don't eat it.

19 casualties in Kriewald in 1921.
450 casualties in Oppau in 1921.
Several hundred casualties in Tessenderlo in 1942.
Several hundred casualties in Texas City in 1947.
29 casualties in Brest in 1947.
31 casualties in Toulouse in 2001.
18 casualties in Mihăileşti in 2004.
161 casualties in Ryongchon in 2004.

[Arkcon]

And ammonium nitrate is harmless.  Just don't eat it.

19 casualties in Kriewald in 1921.
450 casualties in Oppau in 1921.
Several hundred casualties in Tessenderlo in 1942.
Several hundred casualties in Texas City in 1947.
29 casualties in Brest in 1947.
31 casualties in Toulouse in 2001.
18 casualties in Mihăileşti in 2004.
161 casualties in Ryongchon in 2004.

Would you happen to have handy the citation these statistics cam from so we can judge the context for ourselves?

[Borek]

Can't speak for others, but I remember reading about this one before:

http://en.wikipedia.org/wiki/Texas_City_Disaster

[Arkcon]

Oh, okay, so ...

And ammonium nitrate is harmless.  Just don't eat it.

Or accumulate a large amount and ignite it.  Gotcha.