Based on our recent experience, I would say there is little overlap between AP Physics C and AP Chem, and I doubt that the order in which they are taken would make much difference. My twins are both hs seniors, currently taking AP Chem.
They did not actually take AP Physics C (not offered at their school) but self-studied and took the tests last spring (and got 5s). It should be noted that there are two separate AP Physics C (C is for Calculus) tests - Mechanics and Electricity & Magnetism. (Both twins had completed Calc 3 before studying for the tests, and had already taken 1 and 2 years, respectively, of hs Physics. Preparing for the Mechanics exam was a breeze, but self-studying E&M was painful.)
They also had one year of non-honors intro hs Chem as sophomores, i.e., before taking AP Chem. They both find AP Chem pretty easy, and at our parent-teacher conference last week, the Chem teacher said they are having an easy time b/c of their *strong math foundation* and didn't mention physics at all as a factor. That said, note that there is no calculus in AP Chem.
They did do a unit on physical chemistry, but I think that is easily managed without taking AP Physics C.
Last edited by amylou; 11/25/17 04:52 PM.