This really depends on how well you want to do in school. Assuming that you want to do well and get good grades, then expect to study around 8-12 hrs a week for the first year.
At the school I'm at the 2nd year gets exponentially harder and it's not uncommon to have students study 20-25+ hrs a week (I studied more than I ever had during my 2nd year). There's a whole lot of material to be learned and you'd sink if you fall behind. During the 2nd year my typical day consisted of going to class from 8-12 (or until 2 if I have lab), eat lunch, nap, study for two+ hours, dinner, and then either do some leisurely activity or study some more if necessary at night.
It's not too bad, you just gotta pace yourself.
That being said, if you want to just pass, that's not too hard to do. It's fathomable that you can go out almost every night (which some students here do), make straight C's and move on.