# Decomposition of Silver Chloride to Silver



## Beirdo (Feb 2, 2015)

I have been reading several times in various posts here that the way to convert AgCl to Ag is via NaOH + glucose. However, I've also read in several other places (including online university chemistry courses) that AgCl(solid) decomposes to Ag(s) + Cl2(gas) in the presence of sunlight.

I am wondering why this is not mentioned here as an option (although likely not the nicest). Is it:
a) because it seems to be a fairly slow reaction
b) because Cl2 gas is a really nasty gas to deal with
c) some other thing I haven't thought of?

As to chlorine gas being evil... so is NO2, SO2... both gasses that the refiners need to be able to handle at some level... So, I'm a bit confused. I would think that with an appropriate fume hood, and a source of light (I believe I read that it's primarily the UV light that is needed for the reaction?), we should be able to use this to our advantage, no?

I'm sure I'm missing something potentially obvious.


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## Lou (Feb 2, 2015)

Well, this does in fact work. Issue is, it's efficiency.

Unless in a very thin film, light will never fully convert the material to metallic silver.

Probably the best way to convert AgCl painlessly into pure silver is to reduce it with hydrogen gas (or a nonflammable mixture of it and a carrier gas) in a tube furnace. 

2AgCl + H2 --> 2Ag + 2HCl

the gas can be scrubbed (back into azeotropic HCl with water, or caustic to make NaCl) and returned into whatever other process requires it.


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## Beirdo (Feb 2, 2015)

Ah, OK. Yeah, I can see that it wouldn't be terribly efficient. Thanks for entertaining my curiosity on that.

I doubt many of us have a setup that would let us use Hydrogen directly either. heheh.

So I guess that leaves... lye + sugar. Or using the nitrate and avoiding the chloride altogether.

I really do like learning new things. This forum has been excellent for learning not only what can work, but why, and also why some options may be the "it works, but don't do it, it's stupid for X reason" choice. Thanks again


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## MarcoP (Feb 2, 2015)

Would be worth to experiment with a magnetic stirrer under an UV light?


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## goldsilverpro (Feb 2, 2015)

MarcoP said:


> Would be worth to experiment with a magnetic stirrer under an UV light?



Definitely NOT worth an experiment. Like Lou said, very, very inefficient. All that is converted is what's on the surface.


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## Beirdo (Feb 2, 2015)

goldsilverpro said:


> Definitely NOT worth an experiment. Like Lou said, very, very inefficient. All that is converted is what's on the surface.



Yeah, for that to work, you'd need to have it spread out on a large surface, basically one particle thick to be sure the light hits all of it. That doesn't sound too useful to me. It's interesting that the surface of the solid will be silver once it's sat in the light for a while, but really, it would take a long time to be sure that all of the powder has made it to the surface and has decomposed (if it ever all does make it to the surface)... Plus you have chlorine gas to deal with...

Yeah, sounds like a losing proposition, indeed.


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