Where the
world gathers for metal finishing
Q&As since 1989


-----

NH4OH and Silver Chloride

 

I have heard about explosive properties of NH4OH and AgCl2, however, I would like to know why a hammer did not detonate my dried crystals. Process was as follows. CPU chips, known to contain silver bearing solder, were bathed in aqua regia, gold precipitated with sodium metabisulfite, then precipitate covered with NH4OH. Rinsed the gold powder 5 times with hot water, then poured off into separate jar. After approximately 8 hours a thick crust formed on top of this rinse water. After melting it, it turned silvery white. After hitting some of this crystal with a hammer on an anvil, no explosion or any other reaction occurred. Could this not be silver and may be another precious metal? Pd dissolves in aqua regia and would not be present in the NH4OH.

William E [last name deleted for privacy by Editor]
- Midland, Virginia, USA

---

Sorry, William, I don't know enough about what you are doing to understand why it didn't explode -- but I am glad that you didn't blow your hand off at the wrist! Silver fulminates are famous for blowing up at the slightest shake, and I just hope you're doing this experimentation in PPE clothing and in a properly equipped and permitted industrial lab, not a residence. As the salts get a little drier they may choose to explode the next time you slam a door :-)

Good luck.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey