Adding ammonia to silver chloride

[arthur kierski]

When you add ammonia to silver chloride,you make a complex solution where the AgCl is dissolved----could someone tell me if the same happens with sodium hydroxide? if not, what happens?---
thanks for any reply.







Edited by Lou for clarity

 

[Lou]

Arthur, I've edited your post so as to make it clearer to other readers.

Here's a little bit of silver chemistry;

When you dissolve silver chloride in ammonia, you get diamminesilver chloride, that is
AgCl(s) + 2NH3(aq) <----> Ag[(NH3)2]+(aq) + Cl-(aq)

Silver oxide also dissolves up in ammonia.
Ag2O(s) + 4 NH3 + H2O <---> 2 [Ag(NH3)2]+ + 2 OH-

Both of these are soluble. You can break the complex any number of ways, but the easiest is acidification.

Now, when you add base (like NaOH) to AgCl, you will notice that you get a black reaction mix and probably some heat.

2AgCl + 2 NaOH <---> Ag2O + 2 NaCl + H2O

You form a small equilibrium amount of AgOH, but the great bulk of it is Ag2O. Also, this reaction can go backwards or forwards.

Now onto your question:
Adding more base will dissolve the initially formed silver oxide, itself forming a complex that looks like this [Ag(OH)2]- This takes a lot of base. I've never bothered to try and dissolve all of the silver oxide and complex it up. I imagine it would require extremely alkaline (very high OH- concentration) conditions to be stable.

Give it a try and let me know if it all dissolves. At least some of it should dissolve, but OH- is not as good a ligand as ammonia.

 

[arthur kierski]

thanks Lou for your response--i will try with naoh,then exceess and then describe what happened.

 

[butcher]

NOTE:
silver and ammoinia can be dangerous.

 

[SilverNitrate]

Special NOTICE: do not mix ammonia with silver oxide! this is more highly explosive than TNT!

ammonium ligands attach to the silver ion, of silver chloride. This is fine if you're rinsing a tiny amount from a gold drop. however when this silver chloride/ammonium complex set in air it will absorb oxygen and carbon-dioxide and can form the explosive silver azide.

 

[Lou]

This has all been hashed out elsewhere--and it's not silver azide that's formed.

 

[meatheadmerlin]

Here is a thread that covers it.
https://goldrefiningforum.com/threads/silver-chloride-and-ammonia.944/post-13142