Question

Choose the molecule or compound that exhibits dipole-dipole forces as its strongest intermolecular force. a) BCl3 b) N2 c) H2 d) SO2 e) CBr4.

Answer 1

Answer:

SO₂

Explanation:

The dipole-dipole force is not only determined by the electron density around each atoms in the molecule (dependent of electronegativity difference), but also how the atoms in the molecules are arranged. In general, the more symmetric a molecule is, the less dipole force it exerts as each dipole moments cancels each other out.

Now let's examine each answer

• b and c, N₂ and H₂ are composed of same type of atoms, therefore, no dipole moment occurs, and no dipole-dipole forces are exerted
• a and e, BCl₃ and CBr₄ are composed of atoms with different electronegativity, but are symmetric. With BCl₃ having trigonal planar structure and CBr₄ has tetragonal structure, each B-Cl and C- Br bond cancels out each other dipole moment, and thus, no dipole moments were generated.
• d, SO₂ structure is not linear, but is a little bent, this allows net dipole moment to occurs in this molecule as dipole moment from each S=O bond do not cancels each other out