reaction conditions are reflux (ie with heat) with conc. sodium hydroxide. the mechanism is just a standard Sn1 or Sn2 (uni- or di- molecular nucleophilic substition) depending on the haloalkane used. bulkier haloalkanes, eg. tertiary haloalkanes, more likely to perform Sn1 due to steric clash. Would then draw the mechanism on the white board