Why is sulphuric acid not used during the reaction of alcohols with KI?

Explanation

Sulphuric acid is an oxidising agent. It will oxidise HI produced during the reaction to `I_(3)` and therefore, will prevent the reaction between an alcohol and HI to form alkyl iodide.
`2KI + H_(2)SO_(4) to 2KHSO_(4)+ 2HI`
`2HI + H_(2)SO_(4) to H_(2)O+ I_(2) + SO_(2)`
Therefore, a non-oxidising acid such as `H_(3)PO_(4)` is used instead of `H_(2)SO_(4)`.
`CH_(3)CH_(2)OH + KI +H_(3)PO_(4) overset(Delta)to CH_(3)CH_(2)I+KH_(2)PO_(4)+H_(2)O`