My 2018 AP Chemistry Released Exam Draft Answers & Comments appear below. The questions are here. These are DRAFT answers and may change as errors are pointed out to me, and other thoughts come to my mind. Should you find an error PLEASE let me know by commenting on this post below, rather than emailing me or using the contact form me (that way all problems can be addressed in this post), and I will comment/change as necessary.
PLEASE NOTE: Any of my comments below about how your individual answers might be graded, are highly speculative – you should not take them as fact.
Honestly, the exam has a LOT of very easy stuff, but also several places where kids will miss quite a few points. I’d prefer more challenging questions in many places, and I think the boat has been missed on some of those opportunities,
(e)(ii) Will cause issues in terms of moles of reaction. I HATE this concept, and this is a good example of why.
(a) I don’t get the obsession with particulate diagrams, I’m not really sure what they add to the course.
(d)(i) This Lewis diagram ‘fill in’ question around the skeleton is too easy IMO. I think this should be made more challenging.
(f) Obsession over this ‘how the ratio of base to acid makes pH either smaller or larger than pKa’, business. Why?
(a) Although I have no issue with this question myself, many people have commented on how this might cause issues in terms of the excluded Aufbau exceptions. Honestly, I don’t think that it does, BUT it would be smarter for the TDC to steer away from such potential issues IMO.
(c) I SO wish it were still necessary to construct these complex REDOX equations.
(b) My advice? DON’T neglect ‘x’, here!
(a) This may be the first time the SPECIFIC role of the salt bridge has been asked (at least in a contemporary question and from memory). I wonder what might be acceptable here.
(b)(iii) Asks for the answer in J, and you’d think that kJ would be marked ‘wrong’ because of that, BUT on a recent exam a similar thing was asked and either was accepted. What gives?
(b) The interesting part of this is, “are kids supposed to know that radioactive decay is 1st order?”. I suppose we can infer a constant half-life from the Q, but …