Dear NATT!
I can't give you an exact answer, but I wish I could join your experiment! We know so little about the concentrated solutions... Here pH is high, and CO2 dissolves easily: OH- + CO2 <-> HCO3- etc. So, it can be CO2, cause you disturbe the system. But it is more funny, if you put a smoldering stick where the gas leaves, and it begins to shining. The emitted gas can be oxygen! Copper is stable in Cu+ form in alkalines, cause the solution creates reductive environment. And the reaction between Cu2+ and some oxygen(II)-containing components can happen, by the reduction of the Cu2+ ion. And it would give you Cu+ and O2. Please examine the emitted gas! I'm curious... I will do it myself in 10 day's time...
happy new year, NATT!
