Which of the following best represents dipole-dipole forces between two CH3CH2OCH3 (diethyl ether) molecules?

• A. An attraction between the partially positive hydrogen atom of one molecule and the partially negative oxygen atom of another molecule.
• B. An attraction between the partially positive carbon atom of one molecule and the partially negative oxygen atom of another molecule.
• C. An attraction between two oxygen atoms from different molecules.
• D. An attraction between two hydrogen atoms from different molecules.

Answer: (B)

Verified step by step guidance

1. Identify the type of intermolecular forces present in diethyl ether (CH3CH2OCH3). Since it is an ether, it contains an oxygen atom bonded to carbons, but no O-H or N-H bonds, so hydrogen bonding is not possible.
2. Recall that dipole-dipole forces occur between molecules that have permanent dipoles, where a partially positive region of one molecule is attracted to a partially negative region of another molecule.
3. Determine the polarity within the diethyl ether molecule: the oxygen atom is more electronegative than carbon and hydrogen, so the oxygen atom carries a partial negative charge (δ-), while the carbon atoms bonded to oxygen carry a partial positive charge (δ+).
4. Understand that dipole-dipole attractions will occur between the partially positive carbon atoms adjacent to oxygen in one molecule and the partially negative oxygen atom in another molecule.
5. Eliminate options involving hydrogen atoms because there are no highly polarized O-H or N-H bonds in diethyl ether, and oxygen-oxygen attractions are unlikely due to both being partially negative, which would cause repulsion rather than attraction.