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The Organic Chemistry

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Added on  2020-03-28

The Organic Chemistry

   Added on 2020-03-28

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Running head: ORGANIC CHEMISTRY1 Organic ChemistryProfessor’s Name:Name:Date:
The Organic Chemistry_1
ORGANIC CHEMISTRY2IntroductionThe boiling point is defined as the temperature at which a pure substance under normal pressure of 1 atmosphere changes from liquid phase to gaseous phase (Ophardt, 2003). The molecules of a liquid are packed closely and held together by inter-molecular forces of attraction. When a liquid is heated, the molecules acquire kinetic energy resulting to increased vibrations. As more energy is supplied, the vibrations become intense enough to overcome the intermolecular forces and the molecules break free becoming a gas (Ophardt, 2003). Gas molecules are not in contact with each other. The boiling points of organic compounds depend on the strength of the inter-molecular forces between the molecules. Stronger intermolecular forces require a lot of energy toovercome resulting to higher boiling points. Among the common inter-molecular forces include hydrogen bonds, dipole-dipole interactions and Van der Waals (London dispersion forces) (Reusch, 1999). The strongest intermolecular forces are Hydrogen bonds while the weakest are London dispersion forces (Clayden, 2012)The nature of inter-molecular forces of attraction between molecules is dependent on the polarityof the molecules (Ophardt, 2003). Highly polar molecules are held together by very strong intermolecular forces of attraction (Hydrogen bonds and dipole-dipole interactions) leading to high boiling points while non-polar molecules have very weak intermolecular associations (London dispersion forces) leading to low boiling point. The degree of polarity of a molecule is determined by the nature of the functional group present (Ophardt, 2003). Comparison of the boiling points of given compounds.The boiling points of 1-pentanol, 2-pentanol, 2-pentanone and 1-hexanol together with their formulae and molar masses are as tabulated in table 1.
The Organic Chemistry_2
ORGANIC CHEMISTRY3Table1: formula, mass and boiling point of given organic compounds (Lide, 2005; O’Neil, 2001;Haynes, 2014)CompoundMolecular formulaStructural formulaMolar mass (g)Boiling point (0C)1-pentanolC5H12O CH3(CH2)3CH2OH88.151382-pentanolC5H12O CH3(CH2)2CHOHCH388.151192-pentanoneC5H10O CH3(CH2)2COCH386.134102 1-hexanolC6H14O CH3(CH2)4CH2OH102.177157The boiling points of the four compounds increase in the order: 2-pentanone<2-pentanol<1-pentanol<1-hexanol. 2-pentanone has the lowest boiling point while 1-hexanol has the highest boiling point. The differences in the boiling points arise due to differences in the molecular structures of the compounds (Brown, 2000) and the type of intermolecular forces existing between the molecules of each compound (Carrey, 2001). Boiling points of organic compounds increase with increase in molecular mass (Brown, 2000). For compounds with comparable molecular masses, the boiling points depend on the nature of the inter-molecular forces between the molecules. The molecular structures of the four compounds are as shown below.2-pentanone1-pentanonol2-pentanol1-hexanol
The Organic Chemistry_3

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