How Is Arsenic Pentachloride Synthesized?

Arsenic pentachloride (AsCl5) is a highly reactive and toxic chemical compound that is synthesized by the reaction of arsenic trioxide (As2O3) with dry hydrogen chloride gas (HCl) in a specialized reaction vessel. The synthesis proceeds as follows:

1. As2O3 is first heated to a temperature of around 200°C to convert it into arsenic trioxide fumes, which are then passed into a reaction vessel along with an excess of dry HCl gas.

2. The mixture is maintained at a temperature of around 130-140°C for several hours while being stirred vigorously to ensure complete reaction.

3. During the reaction, the HCl gas reacts with the As2O3 fumes to form AsCl5 vapors, which condense and crystallize as a white solid on the cooler parts of the reaction vessel.

4. The excess HCl gas is removed from the vessel under vacuum, leaving behind pure AsCl5 crystals.

The reaction is highly exothermic and must be carried out under carefully controlled conditions to prevent thermal runaway or explosion. Specialized equipment such as glass-lined vessels or stainless steel reactors are typically used to handle AsCl5 due to its corrosive and toxic properties.