Essay on Recrystallization lab report

During recrystallization, the solution was to be cooled to room temperature before placing it in an ice bath. Doing this allows enough time for the crystals to be formed because as the temperature decreases, the rate of crystallization slows down. If the solution was placed in the ice bath too quickly, then the cold would have blocked out the impurities and trapped them in the solution. The more impurities present, the lower the melting point so data would have been inaccurate. Also, if the melting point apparatus wasn’t set up correctly, the data would have been imprecise.

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

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

Solub. Or Reaction w/ hot H20: no change observed from the cool water and is soluble

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.

Substance A and B were weighed; Substance A weighed 0.502 g and substance B weighed 0.503 g. Both substances were put into two different test tube with approximately 8 ml of DI water into the test tub. Substance A and B were stirred and B dissolved while A did not. This shows that B is soluble in water compared to A. Thus, shows that B is soluble in water than A. The reason why B is soluble in water is because it has a higher dipole moment than A. With a higher dipole moment, it shows that it is soluble in water since it is polar and the bonds were easily broken.

For the first lab, students worked individually to purify vanillin, but worked in pairs in order to purify an unknown. We began the process of purifying vanillin by weighing it out and dissolved in water, afterwards we placed the solution in an ice bath. After a minutes, we vacuumed out the vanillin, in order to obtain the crystals. In general, recrystallization is used to purify compounds—which was the purpose of this la . As for the unknown solid, a similar process was conducted. However, for the unknown, students had to determine the right solvent in which the unknown would dissolve in and be used for the

Recrystallization purifies a crude product by separating the product from impurities based on solubility. The product being purified should easily dissolve in the chosen solvent at high temperatures, but not at room temperature. Impurities should dissolve in the solvent at room temperature but not at high temperatures.

Both reactants are soluble and one of the products is a solid. A soluble substances dissolves with water but an insoluble substance doesn't. In a solution, which is a homogenous mixture of two or more substances, one will have a solvent and solute. The solvent

Purpose: The purpose of this laboratory was to gain an understanding of the differences between the freezing points of pure solvent to that of a solvent in a solution with a nonvolatile solute, and to compare the two.

The solution is then cooled and recrystallization of the solute occurs. For a solvent pair to

Reagents 1) Perchloric acid (0.2M). 2)

Generally, increasing temperature would cause a comparable rise in the solubility of liquid and solid solutes in liquid solvents.

If the solute melts prior to the boiling of the solvent, recrystallization will not be able to occur. For example, if you wanted to purify a sample of Compound X which is contaminated by a small amount of Compound Y, an appropriate solvent would be one in which all of Compound Y dissolved at room temperature because the impurities will stay in solution and pass through filter paper, leaving only pure crystals behind. Also appropriate would be a solvent in which the impurities are insoluble at a high temperature because they will remain solid in the boiling solvent and can then be filtered out. Finally, the solvent should be volatile enough as to evaporate from the surface of the compound and be of low financial cost.

SELECTION OF SOLVENTS: Solvent to be included for the formulation of solid dispersion should have the following criteria: