Have you tried a reverse variant of A, where the inner bag contains solid cacl2 (and, to make breaking it easier, some air or some mechanical breaking aid)? If it works it might be safer than A: you will never get solid cacl2 leaking out.
@8petros I would appreciate if you elaborated on the cost/failure point increase (either I don't see something obvious -- it seems to me that everything should be ~comparable -- or I failed to get the difference across).
Unrelatedly, I noticed:
> The solution that remains after the reaction is completely harmless and can be reused as a food additive
or antifreeze liquid.
~1/4 of that liquid is calcium. Daily recommended intake of calcium is on the order of magnitude of 1g. Random sites on the internet claim that taking more than ~3g per day is a bad idea and NHS claims that it can cause diarrhea (https://www.nhs.uk/conditions/vitamins-and-minerals/calcium/). It might be a bad idea to drink that.
That seems to talk about adding it in quantities that cause a person to ingest hundreds of mg of it per day. If you had even a 10g heatpack, you'd need to split it across ~50persondays to be in the same dose ballpark.
The reference for it being considered generally safe in the US lists sub-1% accepted levels in various foods: https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfcfr/CFRSearch.cfm?fr=184.1193
I would appreciate if you elaborated on the cost/failure point increase (either I don't see something obvious -- it seems to me that everything should be ~comparable -- or I failed to get the difference across).
@8petros I'm sorry for being brusque(or something similar; not sure what exactly) and thank you for directness.
What I refer to is that CaCl2 is widely used as a food add-on
Wikipedia on CaCl2 use in food