More particularly, this invention provides an improved process for preparing crystalline ibuprofen of larger average particle size, lower bulk volume and improved flow properties, faster dissolution rate profiles, reduced sublimation rates and better compressibility properties. To our knowledge, ibuprofen is presently crystallized, in commercial scale processes, from commercial hexane or heptane. These aliphatic hydrocarbon solvents characteristically produce ibuprofen crystals which are rod or needle shaped.
Often these are techniques that involve purification of a product.
One common method that can result in losses is recrystallization, where a chemical is first dissolved in a hot solvent and then precipitated out again by cooling the solution, leaving impurities behind.
Often, some of the desired chemical remains in solution, resulting in a reduced recovery.
You can calculate the percent recovery of such a procedure using the starting and ending weights of the chemical. Weigh the chemical product prior to the purification experiment. Ensure the chemical product resulting from your purification procedure is completely free of any residual solvent that might have been used.
If necessary, you can allow the product to sit at room temperature for several days to allow solvent to evaporate or use gentle heating to speed up the process, assuming the product is stable on heating. Sciencing Video Vault Weigh the dry product and record the weight.
Remember to remove any extra material, such as filter paper that might have been used to catch the product during purification; alternately, subtract the weight of that material.
For example, you might have performed the purification by recrystallization of a chemical in a school lab and obtained a dry mass of 2.
Divide the dry mass of the purified product that you just determined by the mass of the chemical you started with prior to the purification process. Note that the mass of the starting material must be in the same units as the purified product.
In the example, if you started with 5. Multiply the result of your last calculation by The result is your percent recovery of that chemical for the procedure.
For the example, you would multiply 0. Common reasons for this include a weighing error and failure to thoroughly dry the product. · determining the concentration of calcium and magnesium from a water sample using AA was taken from the Environmental Protection Agency.
4,5 It was expected that the hardness of the Red River should be significantly higher than the others as it was benjaminpohle.com In order to find the mass percent of water in the sample, I divided the mass of water lost ( g) by the original mass of the hydrate sample ( g) and then multiplied that answer by to find the benjaminpohle.com://benjaminpohle.com · MHS Chemistry Determination of Water in a Hydrate.
A number of ionic compounds contain one or more waters of hydration in their formulas. A good example of this is copper(II) sulfate which exists in an anhydrous form, CuSO4(s), as well as a pentahydrate form, CuSO4•5H2O..
Many anhydrous compounds have a strong tendency to absorb water vapor from the air, thus becoming hydrated benjaminpohle.com · resorcinol in cold and hot solvents of water, petroleum ether, and 95% ethanol were measured.
Before determining which is a better solvent, one should know a good solvent is. A good solvent has certain characteristics that pertain to the solute-solvent mixture as Percent Yield 92% (combined yield) 90% (combined yield) Overall Average benjaminpohle.com This can be approached in two different ways, calculating the percent of water in a hydrate from experimental data or analysis of a chemical formula.
where Delta H f is the enthalpy of melting, Delta H c is the enthalpy of crystallization, and Delta H f,% is the enthalpy of melting for a fully crystalline polymer which you will need to look benjaminpohle.com