I decided to start a new experiment a few minutes ago. It involved household products: sodium chloride, acetic acid 8%, hydrogen peroxide and copper.
I was partially influenced by NurdRage's video about cleaning copper coins (loved it).
I wondered about the possibility of making quickly some copper(II) chloride (I had already left some copper wire in the coin-cleaner solution and it
was making copper chloride, but so slow...). I had then the brilliant idea of adding an oxidizer to the old solution, which left my beautiful
blue-green crystals in a bubbling black bud (cupric oxide).
I decided to start a new experiment. I cut some copper wire into a beaker and added 10-volume hydrogen peroxide (yay for household products
experiments!). I added the acetic acid and the salt. It bubbled intensely. The temperature of the beaker wasn't near 100ºC, so I knew it wasn't
boiling. The bluish to green tinge of copper(II) chloride appeared very quickly in the solution.
Gas continued forming. I know some of it is oxygen gas, but the smell wasn't too comfortable. HCl gas would have reacted with copper, so it cannot
possibly be HCl. It didn't have a smell of acetic anhydride. What on earth is it???
This was one of my first equations:
Cu + 2 NaCl + acetic acid ==> CuCl2 + sodium acetate + H2O
What does the H2O2 do to make it so different? Is it the sodium chloride which catalyses the reaction H2O2 ==> H2O+O2?
Please help me.Hexavalent - 23-9-2012 at 11:05
The peroxide helps the copper oxidize to form bivalent aqueous ions.Eddygp - 23-9-2012 at 11:10
But what about the gases. I already know that the copper is a chloride now, but which gases form, apart from the obvious ones? Hexavalent - 23-9-2012 at 11:20
Some would obviously be oxygen, contributed by the decomposition of the peroxide as well.
It could be partially HCl gas, as it wouldn't all necessarily react with the copper. Depending on the temperature of the solution (or maybe not?),
some of it could have been acetic acid vapours, or perhaps even those of some peracetic acid formed.kristofvagyok - 23-9-2012 at 11:24
What does the H2O2 do to make it so different? Is it the sodium chloride which catalyses the reaction H2O2 ==> H2O+O2?
Please help me.
Copper is only soluble in oxidizing acids, like HNO3, H2SO4, peracetic acid and ect. The H2O2 is needed to make the household vinegar to turn it to
peroxiacetic acid. Also, remember the original producere of copper (II) chloride? HCl and H2O2, it makes active chlorine what will attack the copper.
Normal acetic acid with some table salt won't do anything.Eddygp - 23-9-2012 at 11:25
It actually did... although maybe it was copper(II) acetate, which would explain the cupric oxide formation.Eddygp - 24-9-2012 at 12:19
It is probably acetic acid mist that came out with the oxygen.
