Making silver cyanide from silver nitrate

A. Hi Manoj. If you find Chris & Richard's answers below inadequate, please see
https://patents-google-com.translate.goog/patent/CN1161935A/en?_x_tr_sl=es&_x_tr_tl=en&_x_tr_hl=en&_x_tr_pto=wapp&_x_tr_hist=true
Luck & Regards,


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

!! Hi, Gazi. Silver potassium cyanide is readily available from plating suppliers (you may already know that, but I post it because so many readers assume that they must make up plating solutions from raw chemicals, not realizing that there is a whole robust industry of suppliers offering complete proven silver electroplating processes complete with instruction and technical service.

(Readers: experimenting with silver chemistry and/or cyanide is only for trained and experienced chemists.)

A. It's a one to one relationship between the atomic weights of the various components.

For 107.868 grams of silver (169.87 grams of silver nitrate), it will require 65.12 grams of potassium cyanide. This will produce 133.84 grams of silver cyanide. This is assuming pure, dry chemicals and the total absence of nitric acid.

Any excess of potassium cyanide will dissolve some of the silver cyanide already formed. An excess of 65.12 grams of potassium cyanide will dissolve all of the silver cyanide.

A. I made silver cyanide for eleven years. We made it with a one pound per gallon solution of sodium cyanide (more economical) and an eighty to eight-five troy oz/gallon solution of acidic silver nitrate. The silver nitrate had to have a pH of no more than one. This manufacturing process is done with a great deal of ventilation! Slowly pump the NaCN solution into the agitating AgNO₃ solution (it will get hot) The 'general' ratio used was 33 lbs of sodium cyanide to 1000 tr oz Ag. (adjustments are necessary to finish reaction). The low pH on the AgNO₃ solution was to prevent Ag₂O from forming and creating a grey/brown AgCN precipitant. Test supernatant with HCl; if no turbidity occurs the reaction is complete. Load slurry into fine mesh centrifuge, rinse with DI water until pH is neutral, spin, scrape, dry, grind, package, ship, go home and have a beer.

A. Hi Mike. Yes. of course! Mixing cyanide with acid (hydrogen ions) is how you make hydrocyanic acid gas (hydrogen cyanide). This procedure is for experienced chemists who know cyanide inside out, and as Richard noted: "The silver nitrate had to have a pH of no more than one. This manufacturing process is done with a great deal of ventilation!"

Regards,

Hi cousins. Chris and Richard already answered those questions in substantial detail. Please try your best to frame continuing questions in terms of the highly informative answers already provided -- simply starting a thread over usually only kills it off :-(

Hi Omar. Hopefully you'll get the answers you seek by publicly engaging in the dialog with Fabio and others here. There are an average of a thousand readers for each poster, so one of the reasons we don't help put people into private contact is that it disenfranchises the 999 other readers who were following the discussion ... just when the time they spent tracking down the right conversation is about to be rewarded, the conversation is hijacked and taken private, cutting them adrift :-)

Please keep it all public!
Regards,

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

Thanks Mike. There is no "Cy" in the periodic table, so let's not confuse the school kids who frequent this site :-)

The book you referenced says that the reaction is "of little practical value" -- but I'm not sure why ... maybe it's hard to make practical use of silver cyanide which is so heavily contaminated with nitrates & iron that electroplating from such a solution isn't workable? Good luck.

Regards,

A. I would go about this a little differently.

Make the silver the anode in a divided electrolytic cell, with KCN solution as the anolyte, and KOH the catholyte. This will yield relatively pure AgCN solution.

Or, one could precipitate the Ag from the nitrate solution with sodium carbonate, dissolve in NaCN solution, and "freeze out" the excess carbonate. This will give you NaCN, not KCN, but perhaps you could make that do.