sodium acetate

[yoshhash2]

i am a total newbie here....i understand basic principles like supercooling, phase change, etc, but otherwise a total dummy, i have equivalent to 1st yr university in chem, but that was a long, long time ago. so go easy on me.

 

i am trying to find out the difference btwn sodium acetate trihydrate (used in handwarmers), and anhydrous sodium acetate (used as de-icer). is it the same thing? the former seems to be kind of expensive, sold by the gram, the latter seems to be cheaper, sold by the ton. specifically, i guess i want to know, does the latter share the trait to be easily supercooled?

 

the reason i ask, is i like the potential for sodium acetate trihydrate to "store" heat, and would like to do this in large quantities, but it seems too expensive to do this on practical terms, but anhydrous s.a. seems a lot cheaper, can it do the same?

 

i also would like to know, am i naiive here to think that you can store the heat of summer to be busted out of some huge underground storage facility in the dead of winter? (i know that you would have to separate into small quantities or otherwise you use it all in one enormous reaction.) will it remain in it's supercooled state indefinitely, as long as you don't provide a nucleation point (physically disturbing it, contaminants, etc)?

 

on a similar note, could one do a similar opposite thing with ammonium nitrate?

i am an architecture student, by the way, obsessed with the idea of saving the world thru green architecture.

[DrDNA]

Anhydrous simply means that it is dry.....contains no water.

The trihydrate is not dry. It contains three water molecules for every acetate molecule.

 

One mole of sodium acetate will weigh less than one mole of sodium acetate trihydrate because the trihydrate has the three water molecules. That could be the difference in the price. Anhydrous chemicals are usually more expensive by the mole.

[John Cuthber]

"Anhydrous chemicals are usually more expensive "

Indeed, but not in this case.

I think that stuff sold by the ton is usually less expensive than stuff sold by the gram. Also, the ice melter can be a dreadfully impure product and still work. The handwarmers need to be pretty pure.

 

 

To answer the other part of the question, yes, it could be used on a big scale but it wouldn't be very practical and I'm not sure about ammonium nitrate but I can't see it working much better.

[yoshhash2]

thanks, both of you. john, i wonder though, if you could elaborate on why you think it is impractical. it seems that the sodium acetate could perform as a giant heat (energy) storage tank, one that does not need to be insulated like ordinary hot things, to keep it hot, as long as it is not jarred or otherwise allowed a nucleation point.

 

anything of value (free energy from the sun), which can be stored cheaply and indefinitely, for that euphemistic rainy day, is good, no? what am i missing here?

[John Cuthber]

I think the amount of heat stored would be a bit small for the size of the store. In terms of stored energy you would do better with batteries.