Question: Do rhodium foils dissolve in HCl and bleach?

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MicheleM

MicheleM

Well-known member
Joined
May 4, 2020
Messages
268
Hello everybody,

yesterday I looked for to find the answer to this question but I didn't find it. I'm attempting to identify the metal of wich white-silverish foils coming from contact points of some reed relays are made. Apparently they look resistant to HCl + bleach (at least in the same experimental conditions in which gold foils dissolve). I have excluded ruthenium (no reaction in bleach alone) and tungsten (because no reaction in H2O2 alone) .

Thank you for your attention,
Have a good day!
 
Platinum rhodium and iridium are highly non reactive to most of our standard acid mixes but I believe rhodium should dissolve in hot sulphuric but should you try this do so in a fume hood in very small quantities, fuming sulphuric is really nasty.
 
MicheleM said:
Hello everybody,

yesterday I looked for to find the answer to this question but I didn't find it. I'm attempting to identify the metal of wich white-silverish foils coming from contact points of some reed relays are made. Apparently they look resistant to HCl + bleach (at least in the same experimental conditions in which gold foils dissolve). I have excluded ruthenium (no reaction in bleach alone) and tungsten (because no reaction in H2O2 alone) .

Thank you for your attention,
Have a good day!
Click to expand...
Depends on conditions. Rhodium dissolves in hot concentrated sulfuric acid at appreciable rate only if it is a sponge or powder. Solid Rh like foils are hard to dissolve in sulfuric. It eventualy goes into the solution with HCL/bleach, but it takes good ammount of time.

Once we done batches of testing pins from PCB making factory - some of them were rhodium plated, instead of gold. We dumped it to the AR and let it dissolve. What was left were Rh foils from pins, which were conveniently filtered and thus separated from gold. Some minute ammount was certainly dissolved, but this was very quick way how to get reasonably pure Rh. If the foils didn´t sit in the AR for long time.
 
Thank you very much guys, valuable informations.
I will keep the foils as they are. Rh (and Ir ) chemistry requires a well equipped laboratory that, unfortunately, I do not have.
Thanks again.
 

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