Melting Point and Boiling Point of Organic Compounds

I. LIQUID - Identification of an Unknown Liquid: Using the physical properties of Solubility, Density, and Boiling Point.

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%

Melting points are indicative of identifying an unknown product and the level of impurity the product contains. In this case, the possible identity of the product based on its melting points are determined by comparing the obtained melting points of the product to the melting points of the five possible products. Two mini capillaries, containing the product only, were used to determine the product’s melting point. For one mini capillary, the temperature range was 132.1-134.2℃, and the product’s melting point for the second minicapillary ranged from 135.1-137.5℃. In addition, melting points were obtained with the product mixed with meso-hydrobenzoin. The temperature range was 135.0-136.0℃ and 135.0-137.5℃. Although the recorded melting point values fall into the racemic range, but the results still indicate that the product is a meso-hydrobenzoin. The melting point values for the product mixed with the meso-hydrobenzoin standard explains that it is unlikely that the product is racemic. The melting point values were two degrees from each other due to the meso-hydrobenzoin standard making

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.

What is its melting point? 1,405 K: 1,132 C: 2,070 F. boiling point? 4,404 K: 4,131 C: 7,468 F

If you dissolve a substance such as ordinary table salt (NaCl) in water, the boiling point of the water will increase relative to the boiling point of the pure water. In this assignment, you will dissolve a sample of NaCl in water and then measure the boiling point elevation for the solution.

Though the products had dissimilar melting point values, it is not enough to conclude that they are different. To be certain of the identity of the products, Infrared Spectroscopy (IR) and H- NMR were used. While IR is used to determine the functional groups present in an unknown substance through identification of covalent bonds, H-NMR is used to determine the structure of an unknown compound. The IR from both products had peaks at almost identical frequencies. The IR of both

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

The freezing point of a substance is when the substance turns from a liquid to a solid. The freezing point of a solvent can be decreased by adding a solute and making a solution, which is a freezing point depression. From knowing the temperature difference between a pure solvent and a mixture, it is possible to find the molar mass of the solute.

to portray its pressure/volume/temperature behaviours. We will use the temperature of the boiling water (T), ambient pressure (P), volume (V) and the ideal gas constant (R = 8.31451 J/mol K) to calculate the number of moles (n) of the compound and then, furthermore, the molar mass of the substance.1

Melting range would be closely related to a mixed sample whose constituents are most identical. In other words, melting point will have a wide range and would be below 200°C and above 95°C.

Colligative properties, such as boiling point and freezing point, are dependent on the amount of solutes added, not necessarily their identities (LibreTexts, 2018). A fascinating concept related to freezing points is Supercooling. Supercooling is a state where liquids do not form ice even when they reach temperatures below their normal freezing point; they are trapped in a metastable state (Esrf.eu, 2018). The best example of this is clouds at high altitudes: they contain tiny droplets of water that do not have seed crystals, and therefore do not form ice despite the low temperatures (Esrf.eu, 2018). The concept of freezing point depression is applicable in many parts of everyday life.

The volume is definite if the temperature and pressure are constant. When a solid is heated above its melting point, it becomes liquid, given that the pressure is higher than the triple point of the substance. Intermolecular (or interatomic or interionic) forces are still important, but the molecules have enough energy to move relative to each other and the structure is mobile. This means that the shape of a liquid is not definite but is determined by its container. The volume is usually greater than that of the corresponding solid, the most well known exception being water, H2O. The highest temperature at which a given liquid can exist is its critical temperature.[5]

I was instructed to record a melting point range for each compound, rather than a single temperature melting point. The reason for this instruction is that polymers and unpure substance melt over a range of several degrees. Based on the melting point ranges for both substances, it is difficult to differentiate the two based on its melting point data alone. The ranges of the substances are close enough to one another that one could argue for experimental error when presenting the data as a solo identifying property.

Brittain, C. G. (2009). Using Melting Point to Determine Purity of Crystalline Solids. Retrieved from http://www.chm.uri.edu/mmcgregor/chm228/use_of_melting_point_apparatus.pdf