I just want to say that the later equilibrium chapter passages are absolutely ridiculous. Way, way too difficult and they are in no way reflective of any other material I've seen on MCAT prep and MCAT practice exams. There is absolutely no value in the later passages -- really just an incredible waste of time and they should not have been included.
I want to address your comment, because if you choose not to study those subjects, I think you're making a mistake.
Passage VIII: A lab experiment to determine the concentraion of [Sr2+] in a saturated SrCrO
4 solution. There are three techniques presented and questions focus on camparing the last two.
Passage IX: The results of a qualitative precipitate test similar to one encountered in most general chemistry lab courses. From the precipitate data you have to decide realtive solubilities.
Passage X: A table of K
sps and molar solubilities is given for some salts of zinc, calcium, and silver. Questions ask you typical concepts associated with solubility.
Passage XI: A table of K
sps for calcium salts is given along with an example of a complex equilibrium that can be used to dissolve calcium salts. Questions address concepts like the common ion effect, solubility in varying pH, and relative solubility.
Passage XII: Air pollutants (NO, NO
2, and O
3) are measured over the course of a day. Six reactions are presented (in the form of two sets of three reactions). Using the data in the graph, you are asked to determine how the reactions shift (based on changes in temperature and pollutants).
Passage XIII: The equilibrium of oxygen binding and hypoxia are presented from a general chemistry perspective. This passages mixes basic physiology with basic equilibrium chemistry.
Passage XIV: A textbook staple of N
2O
4 <=> 2 NO
2 is presented. Typical equilibrium and thermodynamics questions are asked.
I'm not sure which topic you feel is not viable for the MCAT, but if you look at the AAMC pdf for physical sciences, you'll see everything above listed there. Some passages may feel difficult at first glance, because they present multiple topics that you may not have seen together before. But if you stick with it and work at each question, you'll come out with a great working knowledge of equilibrium and solubility as well as strong test skills. There will be things on your MCAT that feel hard and look weird, and the best way to prepare for those is to work through weird topics in practice.
As frustrating as it may feel at moments, work through the early difficulties and you'll be amazed at how well things go in the end. Best of luck!
