Which of the Compounds Have Only Dispersion Forces
Introduction:
In chemistry, intermolecular forces play a vital role in determining the physical and chemical properties of substances. These forces occur between molecules and are responsible for determining their boiling point, melting point, solubility, and other characteristics. One type of intermolecular force is called dispersion force, also known as London dispersion force. In this article, we will explore and discuss various compounds that solely exhibit dispersion forces.
Body:
I. Definition of Dispersion Force:
– Dispersion force is an intermolecular force that exists between all molecules, regardless of their polarity or the presence of other intermolecular forces.
– It occurs due to temporary fluctuations in the electron distribution within molecules, resulting in the creation of temporary dipoles.
– Dispersion forces are relatively weak compared to other intermolecular forces such as hydrogen bonding or dipole-dipole interactions.
II. Compounds with Only Dispersion Forces:
A. Nonpolar molecules:
1. Example 1: Methane (CH4)
– Methane is a nonpolar molecule composed of four hydrogen atoms bonded to a central carbon atom.
– As there are no permanent dipoles present, the only intermolecular force acting between methane molecules is dispersion force.
– This accounts for its low boiling point and vapor pressure.
2. Example 2: Ethane (C2H6)
– Ethane is another nonpolar molecule that consists of two carbon atoms bonded to six hydrogen atoms.
– Similar to methane, its intermolecular forces are solely dispersion forces.
– Due to the weak nature of dispersion forces, ethane has a relatively low boiling point.
B. Nonpolar compounds with larger molecular structures:
1. Example 1: Pentane (C5H12)
– Pentane is a larger nonpolar compound compared to methane or ethane.
– As the molecular size increases, the surface area available for temporary dipoles to interact also increases, leading to stronger dispersion forces.
– Therefore, pentane exhibits only dispersion forces.
2. Example 2: Decane (C10H22)
– Decane is an even larger nonpolar compound, consisting of ten carbon atoms and twenty-two hydrogen atoms.
– With an increase in molecular size, the strength of dispersion forces becomes significant due to increased surface area for intermolecular interactions.
– As a result, decane solely experiences dispersion forces.
III. Conclusion:
In conclusion, dispersion forces are present in all molecules, regardless of their polarity. However, certain compounds exhibit only dispersion forces due to their nonpolar nature and absence of other intermolecular forces. Methane, ethane, pentane, and decane are examples of such compounds. Understanding the role of dispersion forces in these compounds helps explain their unique properties, including low boiling points and vapor pressures.
