A dried reflux apparatus with an addition funnel filled with 14 g of sulfuric acid is set up and the RBF is filled with 50 g of phosphorous pentachloride. A vigorous reaction starts upon the slow addition of the sulfuric acid, after which the solution is fractionally distilled in order to separate the two products. The gas outlet of the apparatus during the reaction is placed in a beaker with sodium hydroxide solution to absorb the hydrogen chloride gas.
H2SO4 + 2 PCl5 = 2 POCl3 + Cl2SO2 + 2 HCl
Addition of the H2SO4