Sciencemadness Discussion Board

what did i make? Cu+H20+NaCl+NaOH-=?

hvchem120 - 23-10-2007 at 23:03

so i took about 10 oz of distilled water, added 1/4 of a cup of pure salt, and put a copper pipe into it on both the anode and cathode sides of my electrolysis hookup (50V@400000uf dc) for 10 repetitions (charge up bank, discharge through copper pipe, repeat.) the water at this stage was a bright green and, yes chlorine was emitted by the electrodes. then i filtered it into a 250ml flask (there was some left over, i ended up diluting it and tossing it,) and put it on my hotplate/stirrer and boiled/stirred it until there was only 100ml left. then i added about 1/8 of a teaspoon of red devil lye and it turned bright, transparent blue. then i poured it into a plastic bottle and sealed it and froze it. so now i have purple ice in the bottle and it smells slightly of ammonia. so what did i make? i've taken chemistry in high school, but none in college, i've electrolyzed other things before, but this is different. they've never changed color so vividly before. i wanted to see what would happen, but now i don't know what to do with the result.

woelen - 23-10-2007 at 23:10

The deep blue color of the strongly alkaline liquid can perfectly be explained if ammonia is present and this also is in line with your observation of smelling it. Copper(II) ions form a deep blue complex ion with ammonia and this complex is stable enough to even dissolve Cu(OH)2, giving the complex ion and free hydroxide ions. The formula of the complex is [Cu(NH3)4](2+), it is called tetrammine copper(II).

The only peculiar thing is, where does the ammonia come from? In your description I see no ammonia or ammonium salts added, so the only thing I can imagine is that it is present as a contamination of something.

hvchem120 - 25-10-2007 at 16:09

ok. i don't know where the contamination came from but now what should i do with it? can i dilute it and pour it down the drain, or do i have to take it to a hazardous waste center?

Xenoid - 25-10-2007 at 16:29

Quote:
Originally posted by hvchem120
.....or do i have to take it to a hazardous waste center?


I think you can safely pour it down the drain...:D

Regards, Xenoid

chemkid - 25-10-2007 at 17:23

Next time, consider where you are going with a reaction so you don't end up with something you don't know what to do with. :)

hvchem120 - 25-10-2007 at 21:23

what i wanted was something that i could use to electroplate stuff with copper. however, i don't want an ammonia complex, as it has a tendency to make toxic fumes when heated (eg during electroplating.)

Xenoid - 25-10-2007 at 22:07

If you want to do copper plating, you would be better off starting with some copper sulphate, which is readily available from garden centres, at least around here!

Regards, Xenoid

chemkid - 26-10-2007 at 12:01

Copper sulphate is used for root killers in the US

chemkid

Mumbles - 28-10-2007 at 15:33

It can be found in larger quantities and cheaper as some sort of pond additive. I believe it either kills roots in the pond, or kills algae. Possibly both. It may also be used to give a bit of a blue tinge to the water. I believe I got a 8-10lb bucket for $20.

UnintentionalChaos - 28-10-2007 at 16:58

Pond additive? Copper is highly toxic to aquatic organisms and just about anything else. It is sold as an algecide for swimming pools. It is also sold to kill tree roots growing in your plumbing by flushing a pound or so down the drain.