Sciencemadness Discussion Board

Unknown Copper Reaction

directortelemachus - 13-7-2016 at 18:24

I shoot firearms on a fairly regular basis and to this end I keep a large supply of Hoppes No. 9 bore cleaner on hand. The bottles that No. 9 comes in are rather large so I tried putting some into a small, clean oiling can. I came back a few days later to find that the No. 9 had reacted with the brass of the oiling can and created a rather beautiful green solution. Curious to see if I could replicate the reaction, I poured ~100 mL of the No. 9 into a beaker and placed a single copper (pure) penny in with it. I let the solution sit for a couple of days and returned to find out that indeed, the reaction appeared to have repeated itself. I let this sit for a few more days to ensure a complete reaction. This evening I was sitting at my workbench wondering what exactly what the solution might be and what it might react with. I tried mixing it with a few other things, and found that it reacted again with sulfuric acid (93%), creating a reddish brown liquid. What I found particularly interesting was that when I went to neutralize the solution with a sodium bicarbonate solution, it reacted extremely exothermically and produced a deep purple precipitate.

I was wondering if anyone might have some thoughts on what might be going on here. Below I have included the MSDS for Hoppes No. 9 bore cleaner. I am pretty sure that I can figure out what is happening in the latter part of the reaction, however I'm not so clear on what is happening with the No. 9 at the beginning. I would appreciate any help.

http://www.hoppes.com/Hoppes/files/9d/9dc3db35-232c-4353-bc5...


Addendum: After completely washing the solution in a sodium bicarbonate solution the deep purple color went away. The solution that was left was was clear and colorless.


[Edited on 14-7-2016 by directortelemachus]

TheMrbunGee - 13-7-2016 at 20:20

This is composition of No. 9

1 Ethanol 15 ‐ 40 %
2 Kerosine (Petroleum) 15 ‐ 40 %
3 Oleic Acid 15 ‐ 40 %
4 Amyl Acetate 5 ‐ 10 %
5 Ammonium Hydroxide 1 ‐ 5 %

I don't have the knowledge of any of this stuff reacting with copper metal and forming green salt. Both - the acetate and hydroxide are blue. So there is more complex stuff going on and ingredients co-op to make the green stuff.

Was the red solution clear?

directortelemachus - 13-7-2016 at 20:56

No, the red solution was was opaque. There seemed to be some sort of precipitate in the solution. For what it is worth, No. 9 is supposed to help with coper fouling from jacketed bullets.

[Edited on 14-7-2016 by directortelemachus]

TheMrbunGee - 13-7-2016 at 21:20

Red one is copper (I) oxide.

When adding NaHCO3 - violent reaction is probably it reacting with H2SO4, but I can’t explain the purple color..

Cu2O (red) reacts with H2SO4 to form CuSO4 (blue).

I could assume that Ammonium Hydroxide was still in the solution so it formed complex of some Copper salt, but not CuSO4, because it is deep blue.



Melgar - 14-7-2016 at 12:02

Quote: Originally posted by TheMrbunGee  
Red one is copper (I) oxide.

When adding NaHCO3 - violent reaction is probably it reacting with H2SO4, but I can’t explain the purple color..

Cu2O (red) reacts with H2SO4 to form CuSO4 (blue).

I could assume that Ammonium Hydroxide was still in the solution so it formed complex of some Copper salt, but not CuSO4, because it is deep blue.





Could be a mixture of the red oxide and the blue ammonia complex, perhaps?

TheMrbunGee - 14-7-2016 at 12:10

Quote: Originally posted by Melgar  


Could be a mixture of the red oxide and the blue ammonia complex, perhaps?


Was the purple one clear? if not, then it might be!

directortelemachus - 14-7-2016 at 17:52

The purple solution was very opaque. The color seemed to come from suspended purple particles.

TheMrbunGee - 14-7-2016 at 22:45

Quote: Originally posted by directortelemachus  
The purple solution was very opaque. The color seemed to come from suspended purple particles.


Then those might be just red copper oxide particles in a blue copper solution!(Or red oxide and blue copper carbonate suspension)