Expert: George Maxwell - 2/7/2008

Question
What happenes to napthalene (C10H8) when it is heated? Does it melt?

Answer
Hi, and thank you for your question.

Napthalene at atmospheric pressure normally sublimes (it turns straight from a solid in to a gas), in a similar way to carbon dioxide.

However, napthalene is also very volatile, which means that as you start to heat it, it will quickly form a vapour.

A combination of sublimation and vaporisation therefore happens when napthalene is heated.

Note: Sublimation refers to a substance going straight from its solid form to its boiling point. Vaporization refers to the gradual evaporation of a substance below its boiling point.

E.G. Water put in a saucepan will boil and turn in to gaseous water (steam). Water on a street at normal temperature will slowly evaporate. In both cases, the liquid water is dispersed in to the air - the pan boils dry and the street dries up.

Hope this helps.