Sciencemadness Discussion Board

What was it formed copper(II) hydroxide+acetylene

Vikascoder - 3-4-2012 at 21:46

Hello everybody recently i made copper(II) hydroxide and dissolved in water it was almost sitting at the base of beaker and it was green in colour then i bubbled acetylene into it .the colour of the solution got black from green. I filtrated the solution and got black precipitate . Then i dried it in sun and tried to ignite to check whether it was cupric acetylide but it didnt burn . I want to ask what was it formed.

Brominator - 4-4-2012 at 05:22

Could this not simply be the decomposition of copper (ll) hydroxide in to copper (ll) oxide and the acetylene had nothing to do with the reaction.
also how did u dissolve it in water as isn't copper hydroxide nearly insoluble in water?

bbartlog - 4-4-2012 at 05:39

Quote:
i made copper(II) hydroxide and dissolved in water it was almost sitting at the base of beaker and it was green in colour


If A) it was green and B) you dissolved it in water, then the first problem seems to be that you don't have copper(II) hydroxide. That would be an insoluble blue substance.
However, assuming that you mostly did have cupric hydroxide, then Brominator is probably right. It decomposes easily to CuO.

weiming1998 - 4-4-2012 at 05:50

I agree with the previous two posts. Cu(OH)2 is extremely unstable, to the point that it will spontaneously decompose to black CuO at room temperature (as I observed once). The synthesis of copper acetylide, as described http://en.wikipedia.org/wiki/Copper(I)_acetylide, is by passing acetylene gas through a suspension cuprous chloride with water in the presence of ammonia (or is the solution itself liquid ammonia?). Cuprous chloride might be made from the reduction of CuCl2 with ascorbic acid (vitamin C), found in health stores. `

Vikascoder - 4-4-2012 at 06:37

ya it was completely insoluble sitting at the base of beaker . i unintentionally passed acteylene into it .solution appeared to be green as i was swirling it all around. copper hydroxide is almost insoluble in water. so this process can be used to make copper (II) oxide

weiming1998 - 4-4-2012 at 06:42

Quote: Originally posted by Vikascoder  
ya it was completely insoluble sitting at the base of beaker . i unintentionally passed acteylene into it .solution appeared to be green as i was swirling it all around. copper hydroxide is almost insoluble in water. so this process can be used to make copper (II) oxide


Of course! Either decomposing Cu(OH)2 or CuCO3 (which will also decompose in boiling water) will make CuO.