Experiment No. 1: Melting Point and Boiling Points of Organic Compounds
Experiment No. 1: MELTING POINT AND BOILING POINTS OF ORGANIC
COMPOUNDS
ABSTRACT
The properties of organic compounds depend on their chemical structures.
Intermolecular forces of attraction affect physical properties such as melting and boiling point. Through the Thomas Hoover apparatus, the melting point of 8 test compounds was determined. Salicylic acid exhibited the highest melting point while naphthalene, the lowest. The stronger the intermolecular forces of attraction, the higher the melting point. Boiling point determination was done on 7 different test compounds using micro method. Results show that propanoic acid and n-hexane had the highest and lowest boiling point respectively. The former had the strongest intermolecular force of attraction among the test compounds. Thus, there exists a direct proportionality between intermolecular forces of attraction in a compound and its melting or boiling point. In addition, pure organic solids exhibit a sharp melting point range. I. Introduction
Molecular structures provide an understanding of the physical and chemical properties exhibited by various organic compounds. They account for the forces of attraction that bind molecules of a compound together. Intermolecular forces include dispersion forces, dipoledipole interactions and hydrogen bonding. Dispersion forces, the weakest among the three, are brought about by an instantaneous or induced polarization of molecules. They are also known as van der Waals forces or London forces of attraction. Dipole-dipole interactions exist among polar molecules and are stronger than dispersion forces. A special kind of dipole-dipole force is hydrogen bonding which is the strongest intermolecular force of attraction.
This is present among molecules with hydrogen bonded to an electronegative atom (F, O or N).
Physical properties such as boiling point and melting point are largely influenced by these intermolecular forces. The melting point of a solid compound refers to the
COMPOUNDS
ABSTRACT
The properties of organic compounds depend on their chemical structures.
Intermolecular forces of attraction affect physical properties such as melting and boiling point. Through the Thomas Hoover apparatus, the melting point of 8 test compounds was determined. Salicylic acid exhibited the highest melting point while naphthalene, the lowest. The stronger the intermolecular forces of attraction, the higher the melting point. Boiling point determination was done on 7 different test compounds using micro method. Results show that propanoic acid and n-hexane had the highest and lowest boiling point respectively. The former had the strongest intermolecular force of attraction among the test compounds. Thus, there exists a direct proportionality between intermolecular forces of attraction in a compound and its melting or boiling point. In addition, pure organic solids exhibit a sharp melting point range. I. Introduction
Molecular structures provide an understanding of the physical and chemical properties exhibited by various organic compounds. They account for the forces of attraction that bind molecules of a compound together. Intermolecular forces include dispersion forces, dipoledipole interactions and hydrogen bonding. Dispersion forces, the weakest among the three, are brought about by an instantaneous or induced polarization of molecules. They are also known as van der Waals forces or London forces of attraction. Dipole-dipole interactions exist among polar molecules and are stronger than dispersion forces. A special kind of dipole-dipole force is hydrogen bonding which is the strongest intermolecular force of attraction.
This is present among molecules with hydrogen bonded to an electronegative atom (F, O or N).
Physical properties such as boiling point and melting point are largely influenced by these intermolecular forces. The melting point of a solid compound refers to the
References: Lim-Sylianco, C. (1994). Principles of Organic Chemistry Morrison, R. & Boyd, R. (1987).