Greetings,
Properties of halogenated hydrocarbons are the focus for this post. We'll first look at what they are; then we'll turn our attention to halogenated hydrocarbons possessing very interesting thermodynamic properties (the CFC's - chlorinated fluorinated carbon compounds).
Halogenated hydrocarbons are hydrocarbon compounds with their hydrogen atoms removed and replaced with atoms of the Halogen family of elements. Either all or some of the hydrogens may be replaced by halogen atoms. A few common halogenated compounds are the solvents; Dichloromethane (CH2Cl2), Chloromethane (CH3Cl) and Tetrachloromethane (aka, methyltetrachloride, CCl4). These chlorinated methane compounds all have much higher boiling points than their parent compound, methane. This is due to the much greater polarizibility of the chlorine atom compared to the hydrogen atom. Because the chlorine atom contains so many more electrons than hydrogen (17 vs. 1), there is a much greater probability of uneven electron distribution at any given moment. The result is many more molecules containing chlorine in a temporary dipole state. Consequently, VanderWaals intermolecular forces are relatively strong, giving chlorinated hydrocarbon solvents high boiling points.
CFC's have greatly different properties than chlorinated hydrocarbons. These are due to the very weak London Dispersion forces associated with fluorine atoms. The electrons of fluorine are much closer to the nucleus and so produce much weaker temporary dipoles. The result is weaker London dispersion forces and a much lower boiling point. Because CFC's are gases at room temperature, they are much more compressible than chlorinated hydrocarbons. This compressibility, combined with boiling points near 0 deg. C, make CFC's excellent refrigerants. The following diagram shows a comparison of a common CFC molecule and Chloromethane molecules, along with boiling points of the associated compounds.
That's all for this post. As always, thank you for reading!
A Publication of http://ExcellenceInLearning.biz
Properties of halogenated hydrocarbons are the focus for this post. We'll first look at what they are; then we'll turn our attention to halogenated hydrocarbons possessing very interesting thermodynamic properties (the CFC's - chlorinated fluorinated carbon compounds).
Halogenated hydrocarbons are hydrocarbon compounds with their hydrogen atoms removed and replaced with atoms of the Halogen family of elements. Either all or some of the hydrogens may be replaced by halogen atoms. A few common halogenated compounds are the solvents; Dichloromethane (CH2Cl2), Chloromethane (CH3Cl) and Tetrachloromethane (aka, methyltetrachloride, CCl4). These chlorinated methane compounds all have much higher boiling points than their parent compound, methane. This is due to the much greater polarizibility of the chlorine atom compared to the hydrogen atom. Because the chlorine atom contains so many more electrons than hydrogen (17 vs. 1), there is a much greater probability of uneven electron distribution at any given moment. The result is many more molecules containing chlorine in a temporary dipole state. Consequently, VanderWaals intermolecular forces are relatively strong, giving chlorinated hydrocarbon solvents high boiling points.
CFC's have greatly different properties than chlorinated hydrocarbons. These are due to the very weak London Dispersion forces associated with fluorine atoms. The electrons of fluorine are much closer to the nucleus and so produce much weaker temporary dipoles. The result is weaker London dispersion forces and a much lower boiling point. Because CFC's are gases at room temperature, they are much more compressible than chlorinated hydrocarbons. This compressibility, combined with boiling points near 0 deg. C, make CFC's excellent refrigerants. The following diagram shows a comparison of a common CFC molecule and Chloromethane molecules, along with boiling points of the associated compounds.
That's all for this post. As always, thank you for reading!
A Publication of http://ExcellenceInLearning.biz
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