In the osmometer procedure, what initiates crystallization?

In the osmometer procedure, crystallization is typically initiated by rapidly vibrating the sample to introduce air bubbles, which act as nucleation points for the formation of crystals. When the sample is perturbed, these tiny air bubbles provide surfaces for solute particles to aggregate around, facilitating the orderly arrangement of molecules into a crystalline structure. This method is effective in breaking up supersaturation and triggering phase changes in the solution.

The other methods, such as heating the sample tube or adding a chemical reagent, do not specifically initiate crystallization in this context. While heating can dissolve solutes more effectively, it does not promote crystal formation once the solution cools again unless something else is altered in the process. Similarly, cooling the sample to its freezing point can change the state of the solution, but without proper nucleation sites (like air bubbles), crystallization may not occur efficiently. Thus, the act of rapidly vibrating the sample is the most direct way to encourage crystallization through physical agitation.