Question- Part 1) Doctors sometimes spray ethyl chloride on the skin to momentarily freeze it for minor operations. Explain how this works considering that ethyl chloride is a very volatile liquid with a relatively low boiling point.

Part 2) Sketch two water molecules and show what portions of the molecules can attract when they are in close proximity.

Part 3) Classify each of the following diatomic molecules/ions as polar or nonpolar.

A) HF

B) Cl2

C) CN-

Part 4) Does the nature of intermolecular forces change when a substance goes from a solid to a liquid, of from a liquid to a gas? What causes a substance to undergo a phase change?

Show all work, use additional paper if necessary.