I know that HCL will break when put into water. I also know that Oxygen is more electronegative than Chlorine.
However electronegativity cannot be the reason why oxygen is able to remove the Hydrogen from the chlorine. Since the reaction is such
H2O + HCL => [H3O+] and CL-
The Oxygen is not competing for electrons, with chlorine since oxygen uses two of its own electrons and grabs hydrogen and the bond between chlorine and hydrogen in HCL throws all of its e- onto chlorine itself making chlorine negative.
Perhaps it has to do with atomic orbitals and geometry. The chlorine bond is between a 1s and 3p orbital. While an oxygen bond is between a 1s and 2sp3. I'm thinking that the stability gained from this is the driving reaction to create a chlorine Ion.