Reaction between phosphorus pentachloride and sulfuric acid? I am a novice in chemistry. While reading a magazine, I stumbled on some information about phosphorus pentachloride and sulfuric acid. Phosphorous pentachloride and sulfuric acid are both good dehydrating agents. What is the reaction between them (at standard temperature and pressure).
First phosphorus pentachloride reacts with sulfuric acid to form the intermediate(thanks @bon) chlorosulfonic acid. See here. Also Wikipedia

$$\ce{H2SO4 + PCl5 → POCl3 + HSO3Cl + HCl~~~~~~~~~~~~~~~~~~(1)}$$

Chlorosulfonic acid is actually an intermediate between  sulfuryl chloride  and sulfuric acid. After the formation of the intermediate, the reaction will proceed forward to form stable sulfuryl chloride. (Here)

$$\ce{HSO3Cl + PCl5 → POCl3 + SO2Cl2 + HCl~~~~~~~~~~~~~~~~~~~(2)}$$

Adding (1) and (2), we get the final reaction:

$$\ce{H2SO4 + 2PCl5 -&gt;2POCl3 + SO2Cl2 + 2HCl}$$

My reaction is same as that of Vishnu JK's reaction and bon.