Based on their composition and structure, list CH₂Cl₂, CH₃CH₂CH₃, and CH₃CH₂OH in order of (c) increasing surface tension

Verified step by step guidance

1. Identify the molecular structure of each compound: CH$_2$Cl$_2$ (dichloromethane), CH$_3$CH$_2$CH$_3$ (propane), and CH$_3$CH$_2$OH (ethanol).
2. Consider the types of intermolecular forces present in each compound. CH$_2$Cl$_2$ has dipole-dipole interactions due to its polar nature, CH$_3$CH$_2$CH$_3$ has only London dispersion forces as it is nonpolar, and CH$_3$CH$_2$OH has hydrogen bonding due to the presence of an -OH group.
3. Recall that surface tension is influenced by the strength of intermolecular forces: stronger intermolecular forces result in higher surface tension.
4. Compare the strength of intermolecular forces: hydrogen bonding (strongest) > dipole-dipole interactions > London dispersion forces (weakest).
5. Arrange the compounds in order of increasing surface tension based on the strength of their intermolecular forces: CH$_3$CH$_2$CH$_3$ (weakest) < CH$_2$Cl$_2$ < CH$_3$CH$_2$OH (strongest).

Key Concepts

Surface Tension

Surface tension is a physical property of liquids that describes the elastic-like force at the surface, caused by the cohesive forces between liquid molecules. It is influenced by intermolecular forces, such as hydrogen bonding and van der Waals forces. Liquids with stronger intermolecular forces typically exhibit higher surface tension, as the molecules at the surface are pulled inward more strongly.

Intermolecular Forces

Intermolecular forces are the forces of attraction or repulsion between molecules. They include hydrogen bonds, dipole-dipole interactions, and London dispersion forces. The type and strength of these forces significantly affect the physical properties of substances, including boiling point, melting point, and surface tension. For example, molecules with hydrogen bonding, like alcohols, generally have higher surface tension than non-polar molecules.

Molecular Structure and Polarity

The molecular structure and polarity of a compound play a crucial role in determining its physical properties. Polar molecules, which have a significant difference in electronegativity between atoms, tend to have stronger intermolecular forces compared to non-polar molecules. In the context of the given compounds, the presence of polar functional groups, such as hydroxyl (-OH) in CH3CH2OH, increases surface tension due to enhanced hydrogen bonding compared to non-polar hydrocarbons.