Greetings,
This post is the first of many on properties (Function) of Organic Compounds, with a focus on alkane hydrocarbons. Boiling temperature of simple alkanes is found to be a function of their molar mass, but increasing molar mass is directly linked to increasing London (dispersion) forces between molecules.
A more massive molecule is also a larger molecule. A larger molecule is more likely to contain temporary dipole moments because more electrons are involved, which also occupy larger molecular orbital spaces. Larger molecular orbitals will allow a greater separation of electrons across the molecule leading to a stronger temporary dipole with stronger dispersion forces as a result. Greater intermolecular attractions will result in an increased amount of kinetic energy necessary to separate molecules. An increased amount of kinetic energy is indicated by an increased temperature. The increased temperature is the boiling point when the molecules are completely separated from the liquid state.
The following diagram provides a summary of Boiling Point vs. Molar Mass for simple alkanes.
The following Chart shows the relationship graphically.
As the data shows, there is a clear relationship between boiling point and molar mass for simple alkanes (straight chain). Because molar mass is directly proportional to the strength of intermolecular forces, we can conclude that the boiling temperature of a simple alkane depends upon the magnitude of London Forces between its molecules.
As always, Thank you for reading!
A Publication of http://ExcellenceInLearning.biz
This post is the first of many on properties (Function) of Organic Compounds, with a focus on alkane hydrocarbons. Boiling temperature of simple alkanes is found to be a function of their molar mass, but increasing molar mass is directly linked to increasing London (dispersion) forces between molecules.
A more massive molecule is also a larger molecule. A larger molecule is more likely to contain temporary dipole moments because more electrons are involved, which also occupy larger molecular orbital spaces. Larger molecular orbitals will allow a greater separation of electrons across the molecule leading to a stronger temporary dipole with stronger dispersion forces as a result. Greater intermolecular attractions will result in an increased amount of kinetic energy necessary to separate molecules. An increased amount of kinetic energy is indicated by an increased temperature. The increased temperature is the boiling point when the molecules are completely separated from the liquid state.
The following diagram provides a summary of Boiling Point vs. Molar Mass for simple alkanes.
The following Chart shows the relationship graphically.
As the data shows, there is a clear relationship between boiling point and molar mass for simple alkanes (straight chain). Because molar mass is directly proportional to the strength of intermolecular forces, we can conclude that the boiling temperature of a simple alkane depends upon the magnitude of London Forces between its molecules.
As always, Thank you for reading!
A Publication of http://ExcellenceInLearning.biz
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