Non-Chemical Growing Gold Chloride (III) ?

[Noxx]

Hello,
I'd like to make some Gold Chloride (III) powder or crystals (for photography) but I'm unsure how to perform this. Is AuCl3 sensitive to light ? Also, what would be the best way to form the crystals ? I taught I could dissolve in AR then evaporate to a syrup then add water then evap again.

Any literature on the subject ?

Thanks a lot.

 

[Lou]

This is indeed a very difficult task Noxx.

If you were to dissolve some fine gold up in aqua regia you will have a solution of HAuCl4.

Evaporate that down to a crust and you'll still probably have HAuCl4.
Heat it still more and when it changes from an orange red to a ruby red and loses 1 mole of HCl, you'll have AuCl3. Problems with this: this stuff tends to melt in its own water of crystallisation and it also likes to decompose with exposure to light or temperatures above 150*C. It is exceedingly soluble in water and really hygroscopic so it must be kept in a dessicator. If you were to put a small crystal out on a watch glass and set it about, it would liquefy within a few hours forming the tri-hydrate (which will have some HAuCl4 in it because AuCl3 is a Lewis acid).

If I'm out to make AuCl3 for something I make it in a quartz tube with Au powder and dry chlorine gas, then I get it into an amber glass bottle and package it under dried argon. If I want big crystals I'll recrystallise from an organic solvent (IIRC, acetonitrile works well).

If you were needing a good bit of AuCl3 crystals, I'd either just trade you it for gold on a content basis or just sell some to you.

If you have a tube furnace, quartz tubing, and a cylinder or chlorine (or make it, very easy) and an understanding professor at school, you should try it there! Fun experiment!

 

[Noxx]

Oh I see.
I taught HAuCl4 would become AuCl3
After HCl evaporation...

Thanks for the tips. I'll ask some teachers