Problem dissolving Thiocarbamide

thefizz · Mar 22, 2015

From past experience I have always found thiocarbamide to be slow to disolve but today I was mixing up a proportional bleach and after half an hour of mixing, very little thiocarbamide seemed to be disolved. My stock of thiocarbamide is about one year old so I'm wondering if that would affect how it should dissolve?

Peter

Gerald C Koch · Mar 22, 2015

Its solubility is 9 g/l at 20C. Easily discovered by googling the MSDS.

Rudeofus · Mar 22, 2015

AFAIK there are two forms of Boric Acid, one of which dissolves rather quickly whereas the other one poses some difficulties. While ultimate solubility will be identical between these two forms, it will take very different amounts of time and effort to arrive at or near that limit.

If we now look at thefizz's Thiourea, there is a chance that changed into a form which won't dissolve quickly, or that it changed into some other compound which just happens to be less soluble.

Gerald C Koch · Mar 22, 2015

Rudeofus said:
AFAIK there are two forms of Boric Acid, one of which dissolves rather quickly whereas the other one poses some difficulties. While ultimate solubility will be identical between these two forms, it will take very different amounts of time and effort to arrive at or near that limit.

If we now look at thefizz's Thiourea, there is a chance that changed into a form which won't dissolve quickly, or that it changed into some other compound which just happens to be less soluble.

Some finely powdered chemicals are hard to dissolve because water tends not to wet the powder and they float on the surface. An example is powdered boric acid. When buying it always get the crystalline form.

Rudeofus · Mar 23, 2015

Which leads us to the question: what happened to thefizz's Thiocarbamide? Did it convert into a form which is just more difficult to get into solution, or did it decay? In the first case it's just a matter of patience, whereas in the second case he'd have to throw it out.

thefizz · Mar 23, 2015

I am assuming it is the crystalline form I have as it does not float and there is no mention on the container. I will check with my supplier.

Gerald C Koch · Mar 23, 2015

Again from the MSDS

Chemical Stability
Stable under normal temperature and atmospheric conditions.

Chemical Stability: Conditions to Avoid
Avoid high temperatures, production of dust and incompatible materials. Do not expose this compound to direct sunlight.

It would be helpful to know the exact formula of what was being prepared when the problem was encountered.

thefizz · Mar 26, 2015

Gerald C Koch said:
It would be helpful to know the exact formula of what was being prepared when the problem was encountered.

Proportional bleach as per Tim Rudman:

Iodine 20g
Thiocarbamide 40g
Water to make 1L

Problem dissolving Thiocarbamide

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