Phosphorus pentachloride

Phosphorus pentachloride (PCl₅) is an off-white solid that fumes in damp air, producing hydrogen chloride gas.
For that reason it should be used in a fume cupboard.
When added to ethanol (C₂H₅OH), several observations can be made:

1. There is an immediate vigorous reaction.

2. Steamy irritating fumes (of HCl gas) are observed.

3. Heat is produced.

4. A white smoke forms with a glass rod wet with concentrated NH₃.

Chloroethane, phosphorus oxychloride and hydrogen chloride form.

CH₃CH₂OH  +  PCl₅  →  CH₃CH₂Cl  +  POCl₃  +  HCl