Reaction CuSO4 - NaOH- tatrate-NaCO3 gives (sometimes) a emulsion... Any ideas???

[Sakrelaasta]

Hello to everyone...

 

I am a new at this forum... I am an Environmental Engineer, and I have a big (ok... not so big) question with a reaction I use at my experiments...

 

I have two Reagents:

 

Reagent A: 2% Na2CO3 in 0,1N NaOH

Reagent B: 0.5% CuSO4*5H2O in 1% Potassium Antimony Tartrate (it has blue color because of the Cu)

 

I mix 50ml of Reagent A with 1ml Reagent

 

NOW!!! I have two cases:

At the beginning I was adding to a 50ml volumetric flask filled with the A the 1ml of B

the result was the creation (after something like 1hour) of a bluish emulsion (something I don't want to have)

 

So... I tried once to add the 1ml of B to a beaker filled with the 50ml of A.... The result was that the mixer didn't become a emulsion, but just took a blue-green color... (the one I want!)

 

so.. I found the solution to my problem (use a beaker), but I cannot understand the reason that in the first case the mixer becomes emulsion...

 

 

an idea was that at the volumetric flask the one ml of B was added at the "neck" of the flask (that it is a very small Volume) and so was "trap" and didn't have the time to dissolve to greater volumes, while at the second case the 1ml was added at a bigger volume...

 

So... my question is first of all, do you think the problem is that?? (the small volume at the "neck" of the flask)

and also... has anyone any idea what reaction takes place creating the emulsion??

 

Thank you a lot!!!

Edited August 1, 2011 by Sakrelaasta

[Greg Boyles]

Hello to everyone...

 

I am a new at this forum... I am an Environmental Engineer, and I have a big (ok... not so big) question with a reaction I use at my experiments...

 

I have two Reagents:

 

Reagent A: 2% Na2CO3 in 0,1N NaOH

Reagent B: 0.5% CuSO4*5H2O in 1% Potassium Antimony Tartrate (it has blue color because of the Cu)

 

I mix 50ml of Reagent A with 1ml Reagent

 

NOW!!! I have two cases:

At the beginning I was adding to a 50ml volumetric flask filled with the A the 1ml of B

the result was the creation (after something like 1hour) of a bluish emulsion (something I don't want to have)

 

So... I tried once to add the 1ml of B to a beaker filled with the 50ml of A.... The result was that the mixer didn't become a emulsion, but just took a blue-green color... (the one I want!)

 

so.. I found the solution to my problem (use a beaker), but I cannot understand the reason that in the first case the mixer becomes emulsion...

 

 

an idea was that at the volumetric flask the one ml of B was added at the "neck" of the flask (that it is a very small Volume) and so was "trap" and didn't have the time to dissolve to greater volumes, while at the second case the 1ml was added at a bigger volume...

 

So... my question is first of all, do you think the problem is that?? (the small volume at the "neck" of the flask)

and also... has anyone any idea what reaction takes place creating the emulsion??

 

Thank you a lot!!!

 

You will just get a precipitate containing a mixture of CuCO3 (green) and Cu(OH)2 (light blue).

 

 

As far as I am aware tatrate ion is not a ligand for Cu so reagent A will not eventually dissolve the precipate that forms innitially.