Melting Point Lab

Melting Point Data Table Compound Aspirin Caffeine Salicylamide Actual MP (ºC) 93 - 98 260 - 262 96 - 102 Expected MP (ºC) 135 236 140 Percent Error (%) ~30% ~12% ~30%

These were most likely impurities, in which case I added a bit more water than was necessary. Also, the lab manual says to take two samples of each mixture (unknown; ½ phenacetin; ½ acetanilide) for the melting point, but we only conducted one.

In determining the melting point range of the aspirin, a capillary tube (sealed at one end) was one-third-filled with the dried aspirin. The capillary tube and a thermometer were immersed in an oil bath. The temperature at which the solid started to melt and the temperature when the entire sample was completely liquefied were recorded as the melting point temperature range.

The melting point of benzoic acid is 122.35 °C [5]. The melting point determined from the experiment is a range from 118°C - 120°C. The reason for the experiment producing a melting range compared to a melting point is due to impurities as well for the reason of a lower melting point [1]. Impurities within the product lowers the melting point due to intermolecular forces, this causes benzoic acid to not have as strong of a bond together in its crystal structure as there are impurities in the way. This allows a lower level of heat to melt the benzoic

If the starting cinnamic acid contained the mixture of cis and trans isomers, the product would be the mixture of erythro- 2,3-dibromo-3 phenylpropanoic acid and threo-2,3-dibromo-3 phenylpropanoic acid, which would result in a broad range melting point.

Discussion: As seen in the melting point determination, the average melting point range of the product was 172.2-185.3ºC. The melting points of the possible products are listed as 101ºC for o-methoxybenzoic acid, 110ºC for m- methoxybenzoic acid, and 185ºC for p- methoxybenzoic acid. As the melting point of the sample

Identifying this organic acid was an extensive task that involved several different experiments. Firstly, the melting point had to be determined. Since melting point can be determined to an almost exact degree, finding a close melting point of the specific unknown can accurately point to the identification of the acid. In this case the best melting point

Testable Question: Does the type of material placed on ice affect the rate in which the ice melts? Purpose: When it snows in the winter time or rains and freezes, what can we use to melt away the ice, snow, and sleet faster than salt, if there is anything that melts ice faster than salt. If there is something that can melt the frozen precipitations quickly, it will benefit us. Also, melting the ice at a faster rate will lower the rate of slips and falls even faster.

The results of the IR spectrum contradict those of the mixed compound melting point results which indicated that the same known substance had been mixed in as there was no decrease in melting point.

By using the thermometer correction with Benzoic Acid, the melting point of 122.2C was observed. A 0.2C thermometer correction was used. The range the unknown melt was 149.9C – 153.2C. With the temperature correction, the melting point range was determined to be 150.1C – 153.4C. The crystals completely melted at 153.4C. Adipic acid has a melting point of 153.1C, which is within our observed range2.

Phenacetin had a sharp melting point range (1.4 oC) meant that there was no trace of impurities. The melting point range of acetaminophen was 154.4-155.1oC what was about 15 oC lower than the literature value (169-172 oC); however, experimental melting point of acetaminophen had a sharp melting point range of 0.7 oC demonstrating that the compound was pure. The melting point of tartaric acid was 154.3-157.5oC what was approximately 17 oC lower than expectation. Tartaric acid’s melting point range was 3.2 oC which was not expected for a pure compound, it might be a human error while observing otherwise it might be a trace of impurity in the compound due to a present of solvent such as water1. The melting point of the 9:1 mixture of phenacetin and acetaminophen was 104.3-114.9oC explaining that impurities had lower and broader melting point range. The possible reason to explain why the overall experimental melting points were consistently lower than expectation was a defect of

The actual melting point observed for product 1 was 141⁰C, however, we could not determine the actual melting point for product 2 because it was higher than the thermometer could determine. The maximum temperature product 2 reached was 220⁰C. We did not perform the solubility test ourselves, but a classmate’s results show that product 1 was more soluble in water because it dissolved quicker than product 2 did.

The temperature at which polymer transmit into crystalline form to determine the melting point. The polymer of low-molecular substance exist very low melting point and this happened when polymer chain is dispersed. In physical state melting point is very difficult to calculate. Polymer will decompose at high temperature rather than melts. It is also known as crystalline melting temperature.

Chemistry: Melting points were obtained with an Electro thermal digital melting point apparatus (model 9100) and are uncorrected. IR spectra (KBr) were measured on Perkin-Elemer FT/IR spectrophotometer, 1H-NMR spectra were recorded on JEOL (500 MHz) at Faculty of Science, Alexandria University in DMSO-d6 as solvent, using tetramethyl silane (TMS) as internal reference. Elemental analysis (C, H, and N) and Mass spectra were performed at the Micro analytical Unit of Cairo University using a Vario III CHN analyzer and DI analysis Shimadzu QP-2010 plus mass spectrometer, respectively. The chemical reagents used are Aldrich and BDH.

Melting points were determined on a Perfit melting apparatus (Ambala, Haryana, India) and are uncurrected. UV spectra were measured with a Lambda Bio 20 spectrophotometer (Perkin-Elmer-Rotkreuz, Switzerland) in methanol. Infra red spectra were recorded on Shimadzu FTIR 5000 (FTS 135, Japan) spectrophotometer using KBr pellets; γmax values are given in cm-1. 1H and 13C NMR spectra were screened on advance DRX 400, Bruker spectrospin 400 and 100 MHz instrument in 5 mm spinning tubes at 27 ºC, respectively (Karlesruthe, Germany) using TMS as an internal standard. Mass spectra were scanned by effecting FAB ionization at 70 eV on a JEOL-JMS-DX 303 spectrometer (Japan) equipped with direct inlet probe system. Column chromatography was performed on silica gel (60-120 mesh; Qualigen, Mumbai, India). TLC was run on silica gel G (Qualigen). Spots were visualised by exposing to iodine vapours, UV radiation, and spraying with ceric sulphate solution.