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 the reaction to `l_2` and therefore will prevent the reaction between an alcohol and HI to form alkyl iodide.
`2KI + H_2SO_4 to 2KHSO_4 + 2HI`
`2HI + H_2SO_4 to H_2O + I_2 + SO_2`
Therefore a non-oxidising acid such as `H_3PO_4` is used instead of `H_2SO_4`.
`CH_3 CH_2 OH + KI + H_3PO_4 overset(Delta)to CH_3 CH_2 I + KH_2 PO_4 + H_2O`