Interesting Chemical Reaction

[Igor Chudov @ home]

Eric Cordian wrote:
> Igor writes:
> > An interesting experiment is to mix the ordinary ammonium nitrate
> > (a fertilizer) with room temp. water. Try to put in as much ammonium
> > nitrate as it is possible to dissolve.
> > You will see the temperature of the mixture DROP to below the freezing
> > point (for pure water that is).
> > Wow. I did that 12 years ago and was amazed. A really easy way to get
> > cold water if no freezer is available.
> 
> And for those who may think that endothermic reactions violate some basic
> law about entropy always increasing, I should point out that the increase
> in entropy from the uniform mixing of two different materials can more
> than compensate for the decrease in temperature.  Ain't science wonderful? 

I did understand the above, but thanks anyway Eric. What I still do not
understand though is what happens between the water and ammonium nitrate
that consumes so much energy. 

I mean, okay, you need to spend energy to mix these two things. Then,
logically, they should not "want" to mix, right? But empirically,
ammonuim nitrate literally sucks water vapors from the air. How come?

	- Igor.