I attempted to add powdered creamer to a lukewarm cup of coffee. The stuff doesn’t dissolve well, if at all, but rather floats on the top in clumps. YET! When dissolved into a hot cup which then is allowed to cool down to lukewarm, the clumps do not precipitate out. (Assume equal sized cups of liquid and equal amounts of creamer.)
Why? I know soluability depedns upon temp., so why don’t the clumps form in the latter case? Any Chem folk out there?
In case the chem types show up, can I piggy-back another dissolving question on your thread?
<listening for objection, hearing none, and this will get your topic back to the top, for a minute anyway>
What keeps those chemical deodorizing and cleaning tablets for toilet tanks from dissolving all at once?
Some of them last a really long time.
Shouldn’t something soluble sitting in water all day long dissolve fairly quickly, and not just lose a little bit of blue when the toilet’s flushed?
Energy must be introduced in order to facilitate many chemical reactions. I must admit that I suffered many a forehead bruise trying to sit through a class on colloidal science, but to draw an analogy: you can crack an egg on a cold griddle, and watch as nothing happens, right? Now turn the heat on and watch the egg go from liquid to solid. All that was added was heat. Now turn the heat off. Even when the griddle cools down to room temp or below, the egg will never turn back to liquid. Because it can go from one state to the other but not back again, it’s called an irreversible colloid. Your powdered non-dairy creamer is reversible, but in your case you’d have to remove the water, not the heat. You need to know a little chemistry to be any kind of decent cook, but fortunately most of it is semi-intuitive.
Oh by the way, did I mention that if you subtract one proton & three neutrons from a mercury atom, you get gold? Don’t try this at home.
I’ll give it a shot.
I think that the tablet will dissolve until there is a certain concentration of the deoderizer in the water. After that, no more will dissolve until the toilet is flushed and fresh water is introduced into the toilet tank.
We must blame them and cause a fuss before somebody thinks of blaming us.
Sheila Broflofski
Judy
“Consider it a challenge…”
Here’s non-dairy creamer as explained by the Straight Dope Science Advisory Staff.
In answer to the question about tank tablets, this site is pretty good:
http://www.chem.ualberta.ca/courses/plambeck/p101/p01181.htm
The short story, the chemical dissolves until it reaches saturation, then it stops dissolving. (it doesn’t really stop, it just reaches an equilibrium)
WAG: Creamer powder is light and it floats on the surface. The surface tension of water is high and pushes the little powder grains together. The powder is not in the coffee, it’s on top of it, so it does not dissolve. You have a pile of dry powder floating on the coffee. At the tiny areas of contact, the powder will dissolve.
When you stir the coffee, you break the surface and let the powder mix better, so it dissolves.
opus: Oh by the way, did I mention that if you subtract one proton & three neutrons from a mercury atom, you get gold? Don’t try this at home.
Actually, just one proton less will make it gold, albeit a radioactive isotope of gold. For 197Au (Gold-197), the most common and stable isotope, yes you do need to remove the 3 neutrons.
FYI: 198Au, with a half-life of 2.7 days, is used for treating cancer and other diseases.
This from Los Alamos National Laboratory’s Periodic Table of the Elements.
What would Brian Boitano do / If he was here right now /
He’d make a plan and he’d follow through / That’s what Brian Boitano would do.
The STStaff answer is fine, but it’s the answer to a different (albeit related) question.
I’m not entirely sure that “solution” is an accurate description of the coffee/creamer system. It may be more of a suspension or emulsion. Cream itself is an emulsion (of milkfat in water, with some other stuff like lactose and proteins along for the ride).
That said, let’s continue to think of it as a solution; it’s simpler and it doesn’t really change the answers that much.
There’s probably no thermodynamic barrier to creamer “dissolving” in cold coffee. That is, I think that if you put creamer into cold water and shake it for long enough it will eventually dissolve (even if you keep the temperature down). This explains why it doesn’t precipitate out when the coffee cools back down: it’s perfectly happy in solution.
It just can’t GET there very easily. Most chemical reactions, and lots of things that aren’t technically chemical reactions, happen much faster when you raise the temperature.
I agree. A solution should be clear. The fact that cream is opaque (or translucent, at low enough concentration) means there are little solids floating around - tiny blobs of fat, as I understand.
So the reason powdered cream does not ‘dissolve’ in lukewarm coffee is that it does not melt at low temperatures. Melting the coffee powder breaks it down to smaller blobs, small enough to be considered ‘dissolved.’ Maybe cookie dough is a good analogy - using melted butter results in a more homogeneous mixture than if you just dumped solid butter and stirred the mixture vigorously.
The facts, although interesting, are irrelevent.