Question

Mechanism of Allan's with H2SO4, CH3CH2OH

Answer 1

 that the reaction is preferably called an elimination, rather than a dehydration, although I personally like the term dehydration because it emphasizes the strong dehydrating power of H2SO4 that is unfotunately forgotten too often by undergraduates.   I like to think of it as H2SO4 has such a strong affinity for water that it literally pulls water molecules from organics.