Why does ethanoyl chloride have a lower boiling point that pentanoyl chloride?

This question is referring to the size of molecule and its relation to boiling point. The boiling point is higher when the intermolecular interactions are weaker. Intermolecular interactions are weaker in smaller molecules because there are weaker Van der Waal interactions between molecules, so, because ethanoyl chloride (2 c chain) is smaller than pentanoyl chloride (5 c chain), it has weaker intermolecular bonds and so has the lower boiling point.