Pchem is a lot of differential equations, without that background you won't speak the language.
Most teachers make the class really math heavy, then the ACS final is almost no math, no graphing calculator, and very concept heavy. So if you don't spend some quality time figuring out how to simplify things down to concept level, you'll find that ACS final is an unfamilary beast. But if you get used to the math and what simplifies down to zero in the calculus, how the relationships work: what's proportional, inversely proportional, square proportional, etc.
Basically half of pchem is quantum mechanics, and half is thermo. QM feels a bit more vague to my brain, I don't know half of what it all means but I know the math back and forth--I seriously dream about waveform differential equations even now like 5 years later. Thermo feels very clear and easy. I attribute that to this book which I swear I had memorized at one point: http://www.amazon.com/Laws-Thermodynamics-Very-Short-Introduction/dp/0199572194/ it's truly short so it won't replace a textbook by anymeans, and in addition you should learn the Clausius derivation of entropy.