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I am running experiments using reagents preserved with 0.1% sodium azide, which are applied to a gold film. Unfortunately, there are very few options for using reagents without sodium azide.

I understand that sodium azide reacts with gold to form heavy metal azides, which are explosive.

I would like to know:

  1. How long will it take for sodium azide to react with gold?
  2. Generally, what is going to happen to the gold film?
  3. Any other info you can think of
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  • $\begingroup$ just out of interest, what are the reagents? Is it possible to deactivate the azide and/or move the reagents into a different solvent? $\endgroup$ – Tomcat Aug 8 '13 at 11:09
  • $\begingroup$ Sodium azide can be neutralised using nitric acid. Is this an option for you? $\endgroup$ – Tomcat Aug 30 '13 at 7:27
  • $\begingroup$ Even if it form explosive azide, its going to be so trivial as to not affect your process. Best to ask your chemical supplier if you are unsure. $\endgroup$ – user2617804 Dec 2 '13 at 23:11
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http://www.ehs.neu.edu/hazardous_waste/fact_sheets/sodium_azide/

"Sodium azide reacts with heavy metals (such as silver, gold, lead, copper, brass, or solder in plumbing systems); and metal salts to form an accumulation of the highly explosive compounds such as lead azide and copper azide."

Assume reaction is fast. How many micromoles of gold/cm^2 constitute your film? How many micromoles of azide/volume are in your application? Will the gold be corroded through?

Is the gold there as a convenience or as a necessary surface? A brief soak in dilute decanethiol solution plus rinse will cover the surface with a monomolecular layer of hydrocarbon, each chain being anchored by its sulfur. The surface will be passivated and probably hydrophobic. 1-hydroxy-10-decanethiol will give a hydrophilic surface. Is it worth the bother and expense to diddle with the gold surface?

Gold is selling for $(USD)42.15/g today. How much gold is in your annual discard pile? When my school dumped a load of ancient undergrad combustion bombs I went through them. They originally shipped each with a platinum crucible. One remained. Half a Troy ounce of platinum was a good hour's tax-free wage.

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