Problem with my CuSO4 solution

[NATT]

As we know, the colour of a CuSO4 solution is light blue, I got a green colour in my cuSO4 solution. I suspect that some impurities may have mixed but when i re crystaly it, normal CuSo4 crystels formed. Any ideas?

 

[hermanntrude]

copper sulfate changes colour depending on how hydrated it is. [ce]CuSO4.5H2O[/ce] is blue, as you know, but copper sulfate with less water associated can be greenish, and completely anhydrous copper sulfate is a white powder, which slowly turns greenish blue as it absorbs water from the atmosphere.

 

Of course... it could be impure, too

[UC]

copper sulfate changes colour depending on how hydrated it is. [ce]CuSO4.5H2O[/ce] is blue, as you know, but copper sulfate with less water associated can be greenish, and completely anhydrous copper sulfate is a white powder, which slowly turns greenish blue as it absorbs water from the atmosphere.

 

Of course... it could be impure, too

 

What? I am unaware of any hemihdyrates.

 

is there any chance that this solution contains a lot of chloride anion? Copper (II) ions form yellowish tetrachlorocuprate complexes in solutions with lots of chloride, which result in a green solution, since the water-coordinated copper ions are blue.

[NATT]

copper sulfate changes colour depending on how hydrated it is. [ce]CuSO4.5H2O[/ce] is blue, as you know, but copper sulfate with less water associated can be greenish, and completely anhydrous copper sulfate is a white powder, which slowly turns greenish blue as it absorbs water from the atmosphere.

 

Of course... it could be impure, too

 

The thing it cant b impure is that when i re crystallized it, Nice blue crystals were formed.

If the concentration of CuSO4 is higher than the needed amount,can i add more water till it gets blue in colour?? (Really i added a quite "big" amount of CuSO4. Here CuSO4 is very cheap and abundant :D )

[hermanntrude]

What? I am unaware of any hemihdyrates.

 

is there any chance that this solution contains a lot of chloride anion? Copper (II) ions form yellowish tetrachlorocuprate complexes in solutions with lots of chloride, which result in a green solution, since the water-coordinated copper ions are blue.

 

 

I didnt mention any hemihydrates. I was suggesting just less hydrated than .5H2O

[John Cuthber]

"The thing it cant b impure is that when i re crystallized it, Nice blue crystals were formed. "

Recrystalisation is pretty good at removing impurities so you can get nice blue crystals from a solution that isn't very pure.

 

Also, since solutions of copper sulphate in water are blue and your stuff is green you have an impurity whether you like it or not.

The most probable impurity is chloride as UC explained.

[NATT]

"The thing it cant b impure is that when i re crystallized it, Nice blue crystals were formed. "

Recrystalisation is pretty good at removing impurities so you can get nice blue crystals from a solution that isn't very pure.

 

Also, since solutions of copper sulphate in water are blue and your stuff is green you have an impurity whether you like it or not.

The most probable impurity is chloride as UC explained.

 

haha....i like it

Then bro can the chemical formula may change coz of having exess Cl in this solution????

 

I mean sometimes there may be CuCl ions isnt it????

[hermanntrude]

copper sulfate changes colour depending on how hydrated it is. [ce]CuSO4.5H2O[/ce] is blue, as you know, but copper sulfate with less water associated can be greenish, and completely anhydrous copper sulfate is a white powder, which slowly turns greenish blue as it absorbs water from the atmosphere.

 

Of course... it could be impure, too

 

am I thinking of a different copper salt? i'm sure there's one which can be green or blue depending on the amount of water around

[John Cuthber]

Copper chloride changes colour markedly as it gains and looses water. IIRC the anhydrous form is brown and with increasing water it turns yellow, then green and finally blue.

You won't get CuCl ions but you will get something like a hydrated CuCl+ ion

[Cu(H2O)3 Cl]+