Chemistry 120

Quantitative Chemistry II    Freqently Asked Questions (FAQ)

Spring, 2008

Here you can find answers to many of life's persistent questions - at least those from Chem 120.

Do I need numbered pages in my lab notebook? Mine has bound pages but no numbers.

Yes, but you can add the numbers by hand. Just don't remove any pages, ever - that's not Good Laboratory Practice (GLP).

Can I white-out/erase mistakes in my lab notebook?

NO! All mistakes should be "deleted" with a single line drawn through them, so that they can still be read.

Can I recopy my notebook? It is so messy!

NO!! Never re-copy! The notebook is a record of your work - so it may not be neat, but any recopying alters that record.Recopying is also not GLP.

How should I organize the notebook?

I like to do all of my calculations on the left side (the back of the previous page) and to record all data and all notes from an experiment on the right side. Then I can check my work if I find an error later. I usually set up the right side to record data and leave the left side blank to allow me to calculate.

What do I do with printouts or other data or calculations not recorded by hand?

I suggest making a copy of the printout and fixing it into the notebook permanently with tape or staples, so it can't fall out. If the page contains data they go in the areas reserved for data, if it has calculations, they go with the other calculations.

Is it ok to write data on a piece of paper - like the experiment's results sheet - then record it in the notebook later, so that the data table is neat?

NO! The data always should be recorded directly into the notebook. Never record onto separate paper! And don't do calculations on separate paper, as you will often not be able to find that paper when you need to check your calculations.

Lab and Exam Makeups and Other Issues

Can I attend another lab if I miss lab? I sometimes can't make it to lab during my scheduled lab.

If you have a good reason for missing the lab, you need to contact Prof. Brown and discuss it. We may be able to accomodate you. However, you may not attend another lab without the instructor's permission.

Can I make up or repeat a lab during my scheduled lab? There seems to be time.

Possibly. Many labs have some time built in to permit repeated analyses, and there may be time to work though a mistake made earlier. However, you cannot work past the end of scheduled lab time. Also, a missed lab needs to be discussed with the instructor to allow you to submit results by a different due date.

I broke my buret/pipet and now I need to recalibrate it. Can I attend another lab to do that?

Generally, no. You should be able to do the recalibration in your lab.

I overslept/forgot/was busy during the midterm. When can I take the makeup?

You probably forgot about what it says in the Chem 120 syllabus. Without an excused absence, there are no makeups. With an excused absence, a makeup will be arranged.

Other Requests and Questions

When are the midterms/lab sections/TA office Hours/your Office Hours?

All this and more may be found in the Chem 120 syllabus on line at WebCT and also on the public site. The public site is http://www.udel.edu/chemo/teaching/CHEM120/CHEM120.htm

How do you assign grades in this class?

That is also given in a part of the syllabus. You'll find ranges and the full disclosure of graded material there.

Why are the exams so difficult?

Because it is such a departure from high-school chemistry course material, Chem 119 and 120 have always been challenging to first year students, especially to those with borderline math skills and study habits. Exams focus on homework and concepts from the book and lecture rather closely, but some of these concepts are not easy for students entering the field after a two-year hiatus from chemistry and algebra. Students who put time into the class - and I suggest 9 focused hours per week of study and work outside of class - generally do rather well in this class. I try to make exams somewhat consistent over the years - though not the same - so that the grades in the course can be compared over the years. There is a metric called discrimination in the theory of evaluation[1-3]. That metric indicates an exam that best discriminates between good and weak students should have a mean near 60%, so the goal is an exam that is not too easy but also not impossible for the average Chem or Biochem student taking this class. Note that this does not imply that exams should provide the same experience for all students: students with superior preparation and good math skills will find them very straightforward, while those with little or no real preparation and a weak background will find them very difficult. I am aiming to get an average near 60%, which is a C in the course scoring system. That score plus real effort in the laboratory (where a 70-75% - a B score - is usually the norm) gives a C+ or B- as the average grade in the course.

[1] W.E. Harris, Analyt. Chem. 1975, 47, 1046A.

[2] R.L. Ebel Essentials of Educational Measurement, 2nd Ed., Prentice-Hall, Englewood Cliffs, 1972.

[3] T.L. Kelley, J. Educ. Psychol. 1939, 30, 17.

Do you "curve" the course? What if we all do terribly? What if we all do well?

I don't "curve" classes, but I do recognize that grades are not absolute. Using a curve implies that I am convinced that I always have a truly representative sample from the population of all Chem 120 students out there and that every class does the pretty much the same on exams and overall. Experience has shown that I can't assume that classes behave this way - in fact, my experience is that the student scores have decreased a bit over time. I do have a preset grading scheme which suggests that I can somehow set exams and other tasks that evaluate learning well enough to know that better students will achieve a certain score and weaker students will achieve a lower score. From experience in covering these subjects and in asking certain questions that I know from taxonomy are "easy" and some that are "middle" or "hard," I can test a wide range of skills and learning. Of course, there is always some uncertainty in any measurement, even in grading. To be fair to students that end up near the boundaries of grades, I always "grade up" on exams and "grade up" on decisions to be made concerning grades at the end of the course, so that any uncertainty in the grading occurs in favor of the student. Then, when I assign grades, I can be sure that a person who misses a cutoff is not being unfairly graded. That is generally why you won't usually get me to revise a grade by appeal.

So, if everyone in a class somehow could do all the easy stuff and a lot of the harder stuff, it tells me that the average grade should be near "A". I would award grades accordingly. On the other hand, if everybody in the class couldn't do easy problems and if I didn't see any error in instruction, I could not justify the usual grades here, either, and I would grade accordingly. A curve would see these situations as the same, and would adjust things to generate the same average; experience would say that they are not the same, and would demand that the grades be very different. As the course number goes up, the chance that the most of the students perform well also tends to go up, and so do my grades.

I tried to turn in my homework but the mailroom door was locked. Will you accept it?

The mailroom door in Brown Laboratory gets locked at about 4:30PM, but the homework is due earlier, at 12:00PM. I usually post the homework solutions on-line before lecture, so at 4:30 PM your homework would be past the announced deadline for submission. We generally won't accept late homework.

I can't make your office hours. Can I come to your office to ask questions at another time?

Yes, but because Chem 120 is only a part of my duties, it is possible that I may not have time when you want to see me, especially if you drop in. If you make an appointment, I will keep that appointment, however.

I am having trouble in Chem 120. Is there extra work that I can do to raise my grade?

While I am sympathetic to students who want to do better, my committment to fairness is paramount: everyone in the course gets the same work and the same chance to show me that they can do that work. There is no chance for individual extra work/credit in Chem 120. I will try to help you improve your scores if I can.

I am having trouble in Chem 120. Can you suggest a tutor who can help me?

Mrs. Staib in Room 102 Brown Lab can help you here. She has a list of tutors, courses that they will tutor and their rates. She will provide that list. If you bring me the list, I may be able to give you my opinion on some of the tutors.