RogueRose
International Hazard
Posts: 1594
Registered: 16-6-2014
Member Is Offline
|
|
Sodium Carbonate - Strange reactions when dissolving & allowing to settle
I was mixing a near saturated solution of Na2CO3. I started with 100g monohydrate in about 275-300g 100F water. This dissolved pretty quickly
raising the temp to about 130F and turned the water yellowish/tanish. When it cooled the solution turned into a thick gel-ish substance kind of like
oatmeal but was semi opaque. It seemed to be crystals forming but these were unlike any I had seen before.
Drying the slurry was kind of difficult and the only way was baking in oven as otherwise it popped and spattered all over. I was unable to get any of
the slurry to dry without going to a lower hydrate (it seemed at least). I needed the carbonate in solution for a displacement experiment and I
didn't think it was usable this way so I doubled the water.
Is there something strange with Na2CO3 in how it acts after dissolving? How can I keep it from turning into the slurry or decahydrate (IDK if it was
this, may have been a different hydrate)?
|
|
|
Texium
Administrator
Posts: 4583
Registered: 11-1-2014
Location: Salt Lake City
Member Is Offline
Mood: PhD candidate!
|
|
That shouldn't happen. Where did your sodium carbonate come from?
I've used pool grade stuff before and it's disappointingly impure. It doesn't gel up the way you describe, but it is full of lots of fine particulate
that causes the solution to look yellow, and eventually some fine, brown silt will settle on the bottom. I think it must have some other additives too
because it doesn't behave as expected in reactions.
|
|
|
RogueRose
International Hazard
Posts: 1594
Registered: 16-6-2014
Member Is Offline
|
|
Quote: Originally posted by zts16  | That shouldn't happen. Where did your sodium carbonate come from?
I've used pool grade stuff before and it's disappointingly impure. It doesn't gel up the way you describe, but it is full of lots of fine particulate
that causes the solution to look yellow, and eventually some fine, brown silt will settle on the bottom. I think it must have some other additives too
because it doesn't behave as expected in reactions. |
I suspected that there was something else in it. It is Arm & Hammer washing soda. I'm going to try converting baking soda to washing soda and
see if it does the same or similar. I know the food grade bicarb is supposedly USP quality so there shouldn't be any of the off-color.
I also had the very fine particulate. I filtered the solution and it removed it but the yellowish color remained.
Also, there was a strange smell like funky laundry water (make sense kind of..) not as strong as mixing NaOH and water but a little different.
|
|
|
![[*]](images/xpblue/default_icon.gif){kind=icon}
