[InError]

Hello and thank you ahead of time for your time.

This is more of a curiosity question and I picked what seemed to be the best forum area to post. Apologies if this is not the proper placement.

My family recently purchased some heating pads that make me very curious. What I know of it:

Pads contain a  Sodium Acetate solution with a metal coin/disc. Metal piece has grooves which i assume is for greater mass/reaction. Upon 'clicking' the coin, a reaction takes place with crystallization producing heat. I believe this is exothermic, although I certainly don't have much knowledge here. Boiling pads in water gets it back to a liquid solution to be used again.

My question is:

Would this be something that can be used indefinately? In my mind, granted I am not speaking with any form of certain knowledge, the metal is key. Each time it is used, the molecular reaction 'uses' some of it. Whether this is minimal in amount, I wonder if every time you use it ... you are reducing the composition/mass/etc to the point that one day it couldn't possibly work. Is this accurate or completely inaccurate? Any extended thoughts or understanding would be appreciated.


Regards

[Borek]

Metal is not "used" in chemical sense, it only starts the crystallization mechanically, so in theory it should work forever. But for sure it will just break one day.