The Problem: Let's say we have an experiment where we are attempting to grow rock candy crystals by letting a solution of sugar crystalize on a wooden dowel. However, an error may have been made in that there was too little sugar added for the volume of water to reach saturation and thereby grow the crystals. The solution is to remove some of the water so that the solution becomes saturated.

But that's a problem.

The experimental setup is in an environment were letting it evaporate away is not allowed. It cannot be moved outside or really leave the lab it's in at all. Our access to the setup is very limited and getting resources to it is a logistical and financial nightmare. The test setup may as well be in space. The test apparatus is also not very conducive to modification in that we can't modify it at all and the only access to the solution is through a 3 mm inner dia tube. Repeating the experiment is out of the question because of a whole host of constraints, again assume it's in space.

So my question is, can we send up a molecular sieve to be inserted into the container to absorb some of the water and cause the sugar to reach saturation and thereby start to crystalize? If not, is there something else that can be done to the solution?

Other suggestions must be as harmless as possible. They should also not cause a pressure increase in the container, nor interfere with the growth of the sugar crystals. Any form of density separation will not work.

  • $\begingroup$ Molecular sieves release a lot of heat when exposed to water, if that's a problem then it might not be a good choice. $\endgroup$ – ralk912 Mar 21 '18 at 21:48
  • $\begingroup$ I was unaware of this property. How much is a lot of heat though? The experimental set up can tolerate high heat (~100 C ) and there is plenty of water to serve as thermal mass. $\endgroup$ – Joe Kissling Mar 21 '18 at 21:52
  • $\begingroup$ That's a very good question, I can't tell with numbers. I just know that a way to test if the MS work is to add a few drops of water while keeping them on your hand and if they get really hot, then they're good. $\endgroup$ – ralk912 Mar 21 '18 at 22:33
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    $\begingroup$ A more fundamental problem is that even if the molecular sieve idea worked, the molecular sieves would act as nucleation points for the sugar. So you would likely end up with sugar coated molecular sieves. $\endgroup$ – MaxW Mar 22 '18 at 6:30
  • $\begingroup$ @MaxW that's more preferable than no crystal growth at all. $\endgroup$ – Joe Kissling Mar 22 '18 at 13:18

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