In terms of applying, I honestly think you just need to be passionate about something, even if it isnt career related. The vast majority of schools are happy to have you apply undecided, and many of the pre-professional programs don’t even start until mid-way through your four years. As long as you get in the core courses you need to be an engineer or a doctor, or an MBA, or a dancer, before you graduate, there is still time to try out many random classes along the way. Also plenty of opportunities to change your mind if you find chem engineering is not for you. The pendulum appears to be swinging back the other way now - we heard several colleges - UPenn and Northwestern come to mind - explicitly state that they now want kids who have interests that cross disciplines who will take advantage of several schools within a university while they are there.