Melting Point and Boiling Point of Organic Compounds

2661 WordsNov 22, 201211 Pages
Social Alchemy 2nd Quarter / SY 2012 – 2013 Eng’r. Josephine A. Ng CHM142L/B21 Concepcion, Jermin B. Group# 2 Experiment No. 1 ------------------------------------------------- MELTING POINT AND BOILING POINT OF ORGANIC COMPOUNDS ------------------------------------------------- ABSTRACT The melting point (MP) and the boiling point (BP) are probably the most widely used physical constant in the field of science. Determining the boiling point and the melting point of a compound helps you to characterize an unknown solid in a quick, easy and cheap way. The temperature at which a compound turns from a solid state to a liquid state is known to be the melting point. On the contrary, the boiling point of a compound pertains to the…show more content…
The phenomenon of vapor pressure is interpreted in terms of molecules of liquid escaping into the empty space above the liquid. In order for the molecules to escape from the liquid phase into the vapor phase, the intermolecular forces (in order of increasing strength: Van der Waals, dipole-dipole, hydrogen bonding) have to be overcome which requires energy. Since the nature of the intermolecular forces is determined by the molecular structure, then the amount of energy required to vaporize the sample also depends on the molecular structure. Like melting points, boiling points are characteristic properties of pure materials. However, it requires more material, and because it is less affected by impurities, it is not good to use in determining the purity of organic compounds. Boiling points are approximately related to their molecular weight. The higher the molecular weight, the higher the boiling point. Boiling points are difficult to measure accurately than melting points. The range is often several degrees. EXPERIMENTAL RESULTS: I. Melting Point: A. Structural Effect a. Intermolecular Forces of Attraction COMPOUND | T1 (oC) | T2 (oC) | MELTING POINT | Benzoic acid | 118oC | 124oC | 122oC | Benzoin | 133oC | 140oC | 134oC | Naphthalene | 78oC | 85oC | 82oC | Salicylic acid | 159oC | 160oC | 160oC | Urea | 135oC | 136oC | 133oC | b. Geometric Isomers or Substituents COMPOUND | T1 (oC) | T2 (oC) | MELTING POINT | Maleic acid |
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