Ammonium Nitrate can make ammonia gas?

[navyou14]

Hey! I found a instant cold pack at home which only contained ammonium nitrate and water, but it was already used and all the nitrate salt was dissolved with water! But if i boil the soulution can I get back the nitrate without water and will that produce ammonia gas?

[StringJunky]

It melts at 169.6^oC and boils at 210^oC, so, as long you keep the temperature about B.P. of water to evaporate it you should be left with the solid. Probably the safest way to do it would be to put that solution in suitable heat proof container and then put that in a larger pan of water, and then simmer it until the water has gone out of the solution. Make sure the boiling pan doesn't boil dry. This way, as long as the pan doesn't boil dry, the solution will never exceed 100^oC and melt the ammonium nitrate.

[Enthalpy]

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

You're proceeding over a good wood fire?

[John Cuthber]

In particular, this "This way, as long as the pan doesn't boil dry, the solution will never exceed 100^oC and melt the ammonium nitrate." is simply wrong.

[StringJunky]

In particular, this "This way, as long as the pan doesn't boil dry, the solution will never exceed 100^oC and melt the ammonium nitrate." is simply wrong.

Why? The water in the pan sets the maximum temperature.

Edited May 2, 2015 by StringJunky

[John Cuthber]

oops!

I misread your post.

You are right- in a double boiler/ bain marie like that the temperature will be limited to about 100C.

[StringJunky]

oops!

I misread your post.

You are right- in a double boiler/ bain marie like that the temperature will be limited to about 100C.

Yes, that's what I meant. A thought occurred to me though: presumably, the B.P. of Ammonium Nitrate solution is higher than that of water. Would a plain water bain-marie be hot enough to boil off the water in the solution?

Edited May 2, 2015 by StringJunky

[John Cuthber]

It won't boil the water off from the solution, but it should be hot enough that it will evaporate quite quickly.

It will be quicker if the container with the nitrate solution is shallow.

[StringJunky]

It won't boil the water off from the solution, but it should be hot enough that it will evaporate quite quickly.

It will be quicker if the container with the nitrate solution is shallow.

Yes,.Cheers.

[Sensei]

Once I made such test: is it possible to make distilled water using water bath. Basically hot plate (1200 W @ max settings used) was heating container with water (covered to keep heat inside), inside was placed Erlenmeyer flask with 800 mL water, connected to (single piece) dephlegmator & Graham condenser. I leaved it for several hours.. And 2/3 water evaporated from water bath, and from Graham condenser there was no single drop of distilled water..

 

While using oil bath instead of water (perhaps even salt water bath?) it should work..

 

Addition of substance can decrease or increase boiling point of water.

If ammonium nitrate is increasing solution boiling point, then it'll be hard/impossible/not economical to get rid of water from solution using regular water bath.

But oil bath should work though (kept at reasonable temperature).

Edited May 2, 2015 by Sensei

[StringJunky]

Once I made such test: is it possible to make distilled water using water bath. Basically hot plate (1200 W @ max settings used) was heating container with water (covered to keep heat inside), inside was placed Erlenmeyer flask with 800 mL water, connected to (single piece) dephlegmator & Graham condenser. I leaved it for several hours.. And 2/3 water evaporated from water bath, and from Graham condenser there was no single drop of distilled water..

 

While using oil bath instead of water (perhaps even salt water bath?) it should work..

 

Addition of substance can decrease or increase boiling point of water.

If ammonium nitrate is increasing solution boiling point, then it'll be hard/impossible/not economical to get rid of water from solution using regular water bath.

But oil bath should work though (kept at reasonable temperature).

I think the trick to facilitating evaporation, like JC said, is maximising the suface/volume ratio. Boiling point of cooking oil exceeds the melting point of Ammonium Nitrate, so, you'd definitely need thermostatic control for the oil temperature. It might be slower, using water. but it is easy and will likely suffice to satisfy the OP's curiosity and needs.