Chem 201 Archive – Alan Shusterman

Category: Exams

  • 201 Web Site: Changes & Updates

    I’ve made a number of changes on the web site this weekend. Let me know if there’s something that you’d like to see.

    • Classes page – this replaces the old Syllabus page. Go here to find out what we are covering and when. Also go here to download learning activities, answers, and other in-class handouts. Warnings: 1. I’m still working on the schedule between class #14 (RF before Fall Break) and Thanksgiving. 2. I haven’t found all of the old links to Syllabus yet – if you see one, let me know what URL it appears on.
    • Conferences page – Go here to download conference problems and answers
    • Exams page – Go here to find exam policies, dates, old exams. The latter part of the exam schedule hasn’t been set – stay tuned.

  • Day 14 – Activating OH as a Leaving Group

    I'm providing two documents for Day 14 of class: a reaction summary and my lecture slides. You can find additional summaries in Sorrell (see p.231-2 & 233-5 near end of chapter) and in my learning objectives. Summaries are highly useful ways of expressing the information that needs to be learned and I recommend that you write your own version. Use the 'predict-plan-explain' outline in the Day 14-15 learning objectives to guide what you do (and don't) write down. If your summary takes up more than 1-3 pages, it may be useful, but it isn't a summary.

    Mitsunobu reaction alert. I didn't talk about this reaction in class because I ran out of time, but you need to know the reaction (i.e., know how to 'predict-plan-explain') for the next exam, but you don't need to know all of the subtleties of its mechanism. Just focus on the nucleophilic substitution step: is it SN1 or SN2? what is the ionization state of the Nu? what is the leaving group? There is considerable disagreement about the details of the mechanism. If you're interested, compare Sorrell's mechanism with alternative (and more plausible?) mechanisms presented in Wikipedia and at the Organic Chemistry Portal.

    Exam alert. The next exam (Day 16) covers everything presented through Day 14, including the Mitsunobu reaction. The emphasis will be on Ch. 5 (acid-base), Ch. 6 (SNx reactions of alkyl halides), and only part of Ch. 7 (converting ROH into "RLg" and then RNu). The material from Day 15 will not be on the exam.

  • Test Anxiety Anyone?

    I have found that many more students talk to me after an exam than before. Many more.

    The conversations span all kinds of test-related topics, chief among them, anxiety. For example, any number of students will tell me, “I’m not a good test taker.” The bolder ones will flat out say, “anxiety kept me from studying properly before the test” or “anxiety kept me from doing my best on the test.”

    So it’s good to know that help for anxious test-takers may finally be at hand.
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  • Hg-free Exams? Not quite

    Homework assignment #6 contained an important announcement, but many students who worked on the homework either ignored the announcement or didn’t fully understand it (and many students may not have even seen the announcement given the small number of completed assignments that were turned in).

    Here’s the announcement quoted in its entirety and verbatim:

    Reagent Alert: I will not cover, and I am not going to test you on, the chemistry of Hg(OAc)2 + H2O, then NaBH4, but Loudon uses this reagent extensively in practice problems. Every time you run into this reagent, simply substitute another reagent in its place: H2O + cat. H2SO4.

    And here’s what I saw on HW #6:

    • occasionally replacement of the entire oxymercuration-reduction reagent with H2O + cat. H2SO4 (correct behavior)
    • more often, replacement of parts of the oxymercuration-reduction reagent with H2O + cat. H2SO4. This is incorrect. Do not draw hybrid reagents like “H2O + cat. H2SO4 then NaBH4”. In fact, do not resort to oxymercuration-reduction in this class at all.

    But that’s not all. This reagent-alert does not mean that you should never draw Hg-containing reagents. The activity for class #33 – Alkyne addition reactions: hydrohalogenation and hydration describes the use of salts containing Hg+2 as a method for promoting hydration of alkynes.

    Bottom-line: draw H2O + cat. H2SO4 to hydrate alkenes (Markovnikov) and draw H2O + Hg+2 + H2SO4 to hydrate alkynes (Markovnikov).

  • Contemplating the rest of the semester

    Exam #2 has been graded. Scores are based on a 100-point scale just like the first exam and are written in a box on the last page of the exam.

    You can pick up your exam from Kathy Kennedy on Wednesday of Fall Break, or from Alan on Thursday and Friday of Fall Break.
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  • The Final Exam

    The final exam was a 200 point exam. All kinds of scores were obtained, but they seemed to fall into three groups. Medium-low, medium, and high. Interesting.

    After grading the exam and reflecting on the degree of difficulty, I decided to add 10 points to the “raw score” on each exam to arrive at a “final score”. The following distribution is based on final scores.

    60-79 points – 3 exams
    80-99 points – 14 exams
    100-119 points – 9 exams
    120-139 points – 16 exams
    140-159 points – 8 exams
    160-179 points – 11 exams
    180-200 points – 2 exams

    Median score: 128 points

    If you have questions or comments about the exam, come see me.

  • Last Semester's Paperwork

    I spent a good chunk of winter break buried in paperwork. The stack of final exams, lab reports, and late homework assignments was almost 10 inches thick, but I eventually got through it.

    Now I want it to go away, all of it. Well, not just go away (I could have dumped it in the recycling if I just wanted to make it go away), but actually get it back into your hands where it might do some good.

    Please stop by Kathy Kennedy’s office, room 303, and collect your papers before next Friday, January 29. Thanks.

  • Exam #4 answers

    The answers to the final exam have been posted on the Exams page.

    I haven’t finished reading the exams yet (I’ve read page one of about
    40 exams so far), but an interesting thought occurred to me this past
    week that I wanted to share with you.
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  • The Paper Trail

    I will try to keep you up-to-date by email, but here is where things stand:

    HW #1-7 – everything that I have ever received has been read and returned. If you don’t have your assignment, check the box outside my door. If it isn’t there …

    HW #8 – I am currently reading these and adding them to the papers outside my door. I expect to finish them before I leave work today, but I can’t promise that.

    Exam #1-3 – everything that I have ever received has been graded and returned. If you don’t have your exam, check with Kathy Kennedy, Rm. 303.

    Lab reports – I have returned all lab reports except for the isopentyl acetate (banana oil) and acetylferrocene. I will begin returning some of the isopentyl acetate reports today and that will continue through the weekend. I hope to have them all read by Sunday afternoon, but we will see … You will not be allowed to revise either the isopentyl acetate or acetylferrocene reports. What’s done is done.

  • Q&A session for Final Exam

    Where: Rm. 301, Chemistry
    When: Sunday, Dec 13, 1:45-3:00

    I decided to go with Rm. 301 because the number of students attending these Q&A sessions has fallen considerably. I hope there will be enough room. The Chem 101 people will want to use the room from 3-4 PM so please *ask* your questions during the allotted time. Don’t wait until after its over.