We recommend that you complete all the first and second year courses, including PH 2200, before beginning your junior chemical engineering courses, especially CM 3110.
Although we recommend that you complete PH 2200 before taking CM 3110, you are permitted to take them at the same time or to defer PH 2200 to a later semester. In Fall 2014, 44% of the students taking PH 2200 and CM 3110 at the same time failed CM 3110 or earned a D in CM 3110. Note, also, that PH 2200 is a prerequisite for CM 3310 Process Controls, which is only offered in the spring semester.
If you are not following the standard sequence, please reflect on your capabilities and your academic strengths and weaknesses as you plan your schedule. You may wish to discuss your situation with your advisor. If you are a strong student, you can succeed in CM 3110 even without having completed all your second-year physics. Even strong students, however, will get more out of CM 3110 if they approach it with the full preparation of all the first and second year courses having been completed with a C or better.