You specified C at an IVY league... did you take Ochem 1 at a community college or something? How many classes do you have at your "ivy league" school? If you actually have a 3.55 and can maintain that or go up to a 3.6, you should be ok.
Columbia accepts C's. I read it on their website. They know that a C from Cornell or Brown is not the same as a C from a third tier undergrad college. They know from experience.