Which intermolecular forces are present between two molecules of CH3CH2SH (ethanethiol)?

• A. Hydrogen bonding only
• B. London dispersion forces and dipole-dipole interactions
• C. London dispersion forces, dipole-dipole interactions, and hydrogen bonding
• D. London dispersion forces only

Answer: (B)

Verified step by step guidance

1. Identify the types of atoms and bonds present in the molecule CH3CH2SH (ethanethiol). Note that it contains carbon (C), hydrogen (H), and sulfur (S) atoms.
2. Determine if hydrogen bonding is possible. Hydrogen bonding typically occurs when hydrogen is directly bonded to highly electronegative atoms like nitrogen (N), oxygen (O), or fluorine (F). Since sulfur (S) is less electronegative and not one of these three, hydrogen bonding is less likely here.
3. Recognize that all molecules exhibit London dispersion forces due to temporary fluctuations in electron density, so these forces are always present between ethanethiol molecules.
4. Check for permanent dipoles in the molecule. The C–S and S–H bonds are polar, so ethanethiol molecules have dipole moments, which means dipole-dipole interactions are present.
5. Conclude that the intermolecular forces present between two ethanethiol molecules are London dispersion forces and dipole-dipole interactions, but not hydrogen bonding.