Reaction of chloroalkane. Why chlorine substituted by OH rather than H

[rudders93]

Hi,

I'm abit confused with how this following example works:

Chloromethane reacted with hydroxide ion forms methanol as the chlorine atom is substituted by an OH functional group.

I was wondering why is the chlorine substituted rather than the hydrogen. I get why the OH group substitutes with Cl (since O is more electronegative), but the thing is, Cl is more electronegative (value 3.16 according to http://en.wikipedia.org/wiki/Electronegativity" ) than H (which has a value of 2.20).

So why does this happen? Doesn't Cl have a stronger bond to the Carbon than H does hence it's harder to break?

Thanks!

EDIT: Please move to homework forum? Not exactly sure where this belongs :(

 

[Ygggdrasil]

You should probably read up on leaving groups in an organic chemistry textbook. That should explain why the OH substitutes the Cl and not the H.