In hot melt extrusion, materials are heated, melted and dispersed to be cooled. This process is not suitable for thermolabile products, and the excipients should be miscible in the molten state [12]. Large size particles are produced by hot melt extrusion. Process parameters such as temperature, pressure and mixing rate determines product properties like density, particle morphology, size and size distribution. Table 2 lists the advantages and disadvantages of hot melt extrusion technique [2,5].
The process typically consists of three phases (figure cxxx). First, feeding phase in which excipients enters the heating chamber. Second, the excipients melts and a screw allows its mixing and transfer into the extrusion station. Finally, Extrusion in which the extruder controls the shape and size of the extrudate once is cooled down and cut [12,13].
Co-milling is very efficient in dispersing and homogenizing excipients, it also reduced partiele size in aqueous media. This technique
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The cooling rate has a direct effect on the co-crystal’s size, growth and shape. After co-crystals production, they are then filtered and washed to eliminate impurities. Finally, the crystals are dried, milled and sieved to reduce their particle size [2].
Co-crystallization involves two main steps: nucleation (the material starts its crystallization process on a specific site) which can occur in labile zone that is a zone not optimal for crystal growth, and second the crystal or co-crystal growth. The solid crystals can be formed from liquid, melt or gas, and are more stable than the individual initial materials and held together by non-covalent forces. Compared to the initial material, the co-crystal has a different crystallinity, solubility and mechanical properties
The product was then suspended in 2 ml of water with a stir rod in a 50 ml Erlenmeyer flask and heated to boiling. Water was added in one milliliter increments until all the product was dissolved (18 ml added total). The saturated solution was allowed to slowly cool, and gradual white crystal formation was observed. Recrystallized product was collected once more by suction filtration with the Hirsch funnel once crystallization ceased. Collected product dried on a watch glass for a week, weighed 0.14 g (1.2 mmol), and the melting point was 139°-141°
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.
17) Pour a small amount of the hot solvent into the flask containing the solid.
The vial was removed from the heat and cooled to room temperature. The spin vane was rinsed with 2-3 drops of warm water over the conical vial. The vial was cooled to room temperature then placed in an ice bath for 15 minutes. The liquid was decanted from the mixture and the resulting crystals were dried on filter paper. The crystals were then placed on a watch glass for further drying. The crystals were weighed and a small sample was placed into a capillary tube for melting point determination.
An unknown compound was obtained and the ID number was recorded. A capillary tube was loaded with the unknown powder and inserted into the melting apparatus. The temperatures at which the crystals first started to liquefy and when the entire sample became liquid were recorded. The melting point was then compared with previous known mixture samples to identify the unknown compound.
Substances such as inorganic salts and minerals, semiconductors, and organic and biological compounds can form crystals under suitable and specific conditions. The method is beneficial in determining the structure of molecules, allowing researchers to characterize and understand their behavior and function. This method of structure determination has provided the most reliable evidence scientists have about the way molecules are shaped and what their bonds angles and lengths are. This also can be useful in education, since we can have more of an understanding as chemistry student or even future, nurses or
The first step is the separation of the solid crystals back into separate ions, a positive ammonium ion and a negative nitrate ion. The break these ionic bonds requires a lot of energy which means heat must be taken from the surrounding water. The second step the water molecules, which are H2O, are attracted to the ions and attach themselves to the ions. The second step actually causes heat to be produced to the surrounding liquid mixture. .Even
The purpose of this experiment was to determine which temperature (hot, cold or room temperature) affects the growth of crystals the most.
Once cooled, the mixture was then transferred to a separatory funnel using the funnel while avoiding adding the boiling chip. 10 ml of water was then added to the mixture. The mixture was gently shaken and the phases were allowed to separate. The funnel was then unstopped and the lower aqueous phase was drained into a beaker. 5 ml of 5% aqueous NaHCO3 was added and then shaken gently. A great deal of caution was taken into consideration because of the production of carbon dioxide gas which caused pressure to develop inside the funnel. The pressure needed to be released so the funnel was vented frequently. The phases were allowed to separate and the lower aqueous phases was drained into the beaker. After draining, 5 ml of saturated NaCl was added to the funnel and then shaken gently. Once again, the phases were allowed to separate and the lower aqueous phase was drained into a beaker. An ester product was produced and was transferred into a 25 ml Erlenmeyer flask. This organic product was then dried over anhydrous Na2SO4 to trap small amounts of water in its crystal lattices thus removing it from the product. Finally the ester was decanted, so that the drying agent was excluded from the final product.
Crystals were collected in a Buchner funnel, washed with alcohol, then ether, then transferred into a sample tube for storage.
Minerals are naturally occurring, inorganic, solid, crystalline substances which have a fixed structure and chemical composition. Minerals are an important part of Geology, especially when studying Crystal and mineral growth. Understanding how crystals grow and the difference between slow and fast cooling rates is also important in Geology. Knowing the difference between cooling rates is important because cooling rate changes the texture of rocks and minerals. The purpose for the Crystal Growth experiment is to identify which Solubility and temperature produces larger crystals, and to simulate natural crystal growth. We will achieve the results we desire by conducting the experiment thoroughly and correctly, as well as correctly
To tube 2 and tube 3 a boiling chip is added. The two tubes are boiled to remove any residual ether. Next, the tubes are cooled to room temperature and placed into an ice bath to allow for crystallization. The solution is then removed from the solid in each tube and discarded. To tube 2 and 3 ~0.5 ml of H2O is added for recrystallization, the tubes
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
My hypothesis is that if I add different amounts of sugar to the same amount of boiling water and allow it to be cooled, than the one with the additional cup of sugar will be the one that grows more crystals. I determined that my hypothesis was correct. The glass I chose to add the pure cane sugar did grow much more crystals at a
Spray pyrolysis is one of the simple and cost effective techniques suitable for commercial and mass production of thin film coatings [19]. It is a fast coating process easily applicable for large area depositions at atmospheric conditions. In addition to the inexpensive and simple experimental arrangement, this method has several