Recrystallization Lab

21) After all of the solid dissolves, move the flask from the hot plate and allow it cool to room temperature. After a while, crystals should appear in the flask.

The product was placed in a Craig tube and several drops of hot (100°C) solvent (50% water, 50% methanol, by volume) was added and heated until all of the crystals dissolved. The Craig tube was plugged and set in an Erlenmeyer flask to cool. Crystallization was induced once the mixture was at room temperature by scratching the inner wall of the tube. It was then placed into an ice bath for ten minutes until crystallization was complete. The tube was then

Crystals were collected in a Buchner funnel, washed with alcohol, then ether, then transferred into a sample tube for storage.

It is necessary to heat the mixture in Step 2 of the procedure because without heat, the mixture is unsaturated- it can hold more solute. At a higher temperature, however, the amount of solute added in Step 1 allows for a saturated and then supersaturated solution.

The recrystallization technique utilizes the ability of a compound to dissolve within a hot solvent and produce a solution. As this solution cools, the solute reforms without impurities in a crystal lattice structure.1 For this to work properly, an appropriate solution that will not dissolve the solute at low temperatures, but will at high temperatures, must be used.1 There is no single solvent that will work well for every solute’s recrystallization; different solvents are better suited for some solutes than others.2 Some impurities that do not dissolve within the solvent can be filtered out while the solution is still hot, while other impurities that readily dissolve within the solvent shouldn’t recrystallize with the pure substance (as they are not concentrated enough to

List the basic steps in the recrystallization of acetanilide. Include the identity of the solvent that will be used and what is added before hot filtration.

It can be artificially attained by increasing the kinetic energy of some solutions to allow more solute to dissolve into the solvent; then if a disturbance is created (either by a seed crystal, or an impurity in the solution) the excess solute will fall out of solution. A similar effect can be seen by carefully cooling distilled water, such as in a water bottle, down past the freezing point, carefully removing it from the freezer, and then tapping the container to cause the whole thing to freeze at once.

When the water evaporates slowly from the solution, only a few crystals begin their growth – this also means the crystals have more time to grow large before all the water has dissolved. In comparison, when the water evaporates quickly from the solution, more crystals begin their growth – however, these crystals do not have as much time to grow as large. (“How Does Temp Affect the Growth Rate of Crystals?”

A heat pad was set up in a place free of outside interference, as was the room temperature station and a shelf was cleared in the fridge. Once setup pour 25ml of the crystal solution into each beaker. Once the solution is in mark one beaker as the room temperature, one as the fridge and one as the heat pad.

Cut your string so that the crystal will hang in the center of the solution, and tie your string around your seed crystal, and attach the other end to U-shaped paperclip. (See figure 3)

would normally occur at room temperature. This super saturated solution can be prepared by heating the water up which excites the water molecules and lets more salt, sugar or sodium acetate in this case dissolve between them. Sodium acetate is actually a salt

III. Crystallization is the formation of sugar crystals in a sugar syrup. Crystallization is the natural or artificial process of formation of solid crystals from a homogenous (“the same

The main objective in crystallization is to produce a pure substance. A chemist is able to achieve this by isolating the pure form from the impure form, using methods of dissolving, cooling/crystallizing, and filtration. It is also important to select the best solvent to crystallize the material; the best solvent shows the desired solubility behavior (Pavia et al 26).

If we dissolve sugar and salt in boiling water and pour it into a jar then the salt will form a crystal first because salt is more of a crystalline mineral than sugar.

Recrystallizing solvent is a solvent that shows the desired solubility behavior for the substance to be crystallized. Identifying the ideal recrystallizing solvent of a compound is necessary to purify the organic compound.. In choosing the recrystallizing solvent, the compound should be insoluble at room temperature. While heating, the compound should be very soluble and upon cooling, it is insoluble. The unwanted impurities should be soluble at room temperature or insoluble during heating. The recovered crystals from the final procedure were only half of the