Sciencemadness Discussion Board

Copper Sulfate impurities?

Fidelmios - 25-5-2016 at 16:42

Hello all,

So I've been doing crystallizations of Copper sulfate for over a month now, and I have bought two different amounts of Copper sulfate from the same supplier. The first batch was a fine powder, the second was larger, white coated granules. Since my crystals from the first batch were fairly large I decided to make a new saturated solution and let my old crystals grow even larger. I left them in solution for about a week and came back to a teal/green solution! The solutions were in my refrigerator, to both protect from dust and keep a constant temperature.

I have a few ideas on what may have happened, please tell me if I'm too far off base.
1. The Copper Sulfate solution was near an iron sulfate solution, maybe there was some contamination.
-I think this is unlikely, I recently made another batch of solution and it turned out the same.
2. The Copper Sulfate Solution was more impure than listed.
3. The water I used (tap water) may have done something to the solution. If I remember correctly I had a small amount of this odd stuff last time I made the crystals. I will make a new solution with distilled water and tell you all what happened tomorrow.
-It could be Copper Chloride, or something like that from the tap water depending on its harshness.


Please let me know what has happened. Here is a Link to the images from this morning. The first one is a large crystal, showing a small amount of these green impurities, the last shows my stock solution.

XeonTheMGPony - 25-5-2016 at 17:07

Tap water contains a ton of material that will waste a crystallization.

All ways use distilled water!

Fidelmios - 25-5-2016 at 17:39

I'm pretty sure the impurities are gone now. (hopeing)

Fidelmios - 27-5-2016 at 00:14

Okay, so fast forward a few days and the solutions are still blue green, and damn murky. I even tried making a solution with pure water, and that too has a small tint of green. However, when I heated the solution I boiled the water in a tea kettle, so that may have still had some contaminants. Is it possible for me to recoup my Copper Sulfate?

I was thinking turning it to basic copper carbonate, allowing it to dry, and converting that back to Copper Sulfate with H2SO4