Select the dominant intermolecular force between acetone molecules.

Select the dominant intermolecular force between acetone molecules.

a. hydrogen bonding

b. London dispersion forces

c. ion-dipole forces

d. dipole-dipole forces

Answer: d. dipole-dipole forces

In acetone, the major type of intermolecular force is the dipole-dipole force since it is a polar molecule. The structure of acetone has functional groups, which makes it polar; the carbonyl group (C = O) causes the charges to become uneven within CH₃COCH₃. The oxygen atom is more electronegative than the carbon atom and thus repels electrons more than the carbon atom does thus acquiring a negative charge while donating its electrons the carbon atom acquires a positive charge. These two show polarity with each molecule of acetone having a slight positive and negative charge; this leads to the phenomenon of dipole-dipole intermolecular forces between acetone molecules. These forces come about as a result of the permanent dipole moment possessed by the molecules in which the positive end of one molecule is attracted to the negative end of the other. While the molecules of acetone do undergo London dispersion forces, well known to affect all molecules, the dipoles exert stronger forces and thus have a stronger influence on the properties of acetone, for instance relatively high boiling point for a molecule of its size within the non-polar species. Since there is no hydrogen bonding and no significant ionic components in the structure of acetone, the other options can be eliminated.