Lithium chloride is hygroscopic and rapidly dissolves in the water it absorbs from the atmosphere. Thus, in order to obtain some crystals of lithium chloride we placed a concentrated solution of the salt in an evaporating basin in a desiccator. Solid lithium chloride crystals were formed and when we put samples of them under the microscope, this is what we saw:
Lithium chloride crystal
More lithium chloride crystals as seen under the microscope
We did not observe a cubic structure as we had seen for sodium chloride. In fact we had not seen crystals like this with any of the sodium and potassium halides we had crystallised. See our June 2014 post for images of NaCl, NaBr, NaI, KCl, KBr, KI crystals and some other common salts.
Getting good images of lithium chloride crystals under the microscope was problematic because they started dissolving on the microscope slide as soon as they were taken out of the desiccator.
Lithium chloride crystals dissolving on the microscope slide (speeded up time lapse animation)
This is what you see looking down the microscope (speeded up of course)
Here are three samples of lithium chloride on microscope slides at three different stages of dissolution, some time after we had viewed them under the microscope:
Left to right, three samples dissolving
Here is the apparatus we used to obtain the lithium chloride crystal pictures:
Desiccator in a huge plastic bag on the right, microscope in the centre, computer screen image on the left.
Inside the desiccator
Lithium chloride crystals
We are unsure of the formula of the lithium chloride crystals produced. Lithium chloride monohydrate LiCl.H2O has been reported, as have other hydrates. Or ours may be LiCl or a mixture of the various forms.
We took multiple photos of various samples of the lithium chloride crystals under the microscope and adjusted the focus slightly between shots of each sample. We then put these images into a focus stacking freeware program called Picolay, (which can be obtained here).
Here are our results:
Can’t see the wood…
How would you describe the shapes of these lithium chloride crystals?