Theoretical question (silver chloride conversion)

facesfromparadise · Oct 31, 2016

Hey all, first time asking a question on here. Been a member for quite a few months now just reading. I've done some acquaintance experiments and processed a few things (mylars, fingers, mlccs) with success, largely because of the wealth of information on this forum and it's members generosity, patience and dedication to SAFETY above all. Thank you all for all you do. Now for my question, I didn't see anything else on this when searching but forgive me if this has been discussed already. When AgCl is converted using zinc/iron shavings and dilute sulfuric acid I know that hydrogen gas is displaced from the acid. Now the chemistry knowledge I have picked up both from here and my job (QC analytical lab at a vitamin and food product plant) would lead me to believe that its this H2 gas that is doing the work in reducing the AgCl to Ag and forming HCl. This would be what would require constant motion to prevent the hydrogen gas from simply bubbling out. Is this the case? If so wouldn't it be possible, though likely not practical or it would have been discussed already here

, to simply reduce AgCl under a stream of hydrogen? asking just to have a better understanding of the actual process. Either way it probably wont change the way I process AgCl. Thanks everyone for your time, this is a truly great thing going on here and I consider myself lucky to be in such a fraternity with all you folks. Happy Halloween, dont eat too much candy ;D

Barren Realms 007 · Oct 31, 2016

I'm sure I'm going to be wrong in this post but I'm going to take a shot at it anyway.

Using Iron with a 10% Sulphuric acid solution. If I'm correct you are exchanging a silver chloride ion ( Metalic in it's original form ) with a mettalic Iron ion back to elemental silver metal.

With HCl and silver chloride (Metallic in it's original form ) being converted with zinc/aluminum you are exchanging with a metallic zinc/aluminum ion for the conversion back to elemental silver metal.

With hydrogen there is no metallic ion to exchange with because hydrogen is either a gas or a liquid.

facesfromparadise · Nov 1, 2016

So the way you're thinking about it it's more like direct, cut and dry, galvanic corrosion where two metals (or here a metal and a salt) are in contact in an electrolyte. See I had figured that since zinc is higher on the reactivity series than hydrogen that it would switch places there, forming ZnSO4 (I always use sulfuric, didn't know you could use HCl !) displacing the hydrogen which would then in turn yank the chloride ion off of the silver. Iron should behave that way too I think (don't have series in front of me and I'm on my lousy phone and don't feel like pulling up another tab) it would be interesting to hear more members chime in here, although its not a practical discussion of 'how to get the gold'. for those inclined it's certainly interesting. Thanks barren B)

Lou · Nov 1, 2016

It's probably a little bit of both going on.

Hydrogen gas works on silver chloride because a volatile gas, HCl, is produced and that is the thermodynamic driving force.

Barren Realms 007 · Nov 1, 2016

Lou said:
It's probably a little bit of both going on.

Hydrogen gas works on silver chloride because a volatile gas, HCl, is produced and that is the thermodynamic driving force.

Thanks for that info Lou. I wasn't too positive about that.