Typically, when I see students carrying around the ACS student
study guide or a Medical College Admission Test (MCAT) book
throughout the school year, I know that those students are
more likely than others to do very well in my course. The review
guide (like the MCAT review book) isn’t intended for studying
just for the week before the exam; it can and should be used as
a supplement to your class textbook on a regular basis. When
you cover a subject in class, you can refer to your review book
to see how it is presented (and evaluated) for your standardized
exam. Not only will you be preparing for your future multiple-
choice exam, you will also be reinforcing concepts that will help
you in your course.
Practice creating your own multiple-choice questions.
Multiple-choice questions don’t simply appear from thin air; people
write them. So you can write them, too. Spending some time
making up multiple-choice questions will demystify them (see
below for an example of how to create a multiple-choice question). Also, take some time to think about common mistakes
Breaking down a multiple-choice question
Looking for an effective study technique? Try developing some multiple-choice questions. One method is to rearrange a short-answer question to make it into a multiple-choice question. Many multiple-choice
questions follow the same format: one correct answer, one incorrect
answer with an obvious mistake, and two incorrect answers with common but perhaps less obvious mistakes.
Thinking through common mistakes helps stop you from making
those mistakes yourself! For example, the following short-answer question could easily be worked into a multiple-choice question:
A STUDENT DESIGNS A REACTION BETWEEN
1-CHLOROBUTANE AND SODIUM METHOXIDE IN
DMSO. WHAT SHOULD SHE EXPECT THE OBSERVED
RATE EQUATION TO BE?
This question is testing your knowledge of reactions between primary alkyl halides (like 1-chlorobutane) and strong nucleophiles (like
the methoxide ion) in polar aprotic solvents (like DMSO), which favor
the SN2 mechanism. The rate of an SN2 mechanism is dependent on
both the nucleophile and the substrate, so Rate = k[1-chlorobutane]
[sodium methoxide] is the correct answer.
What are some common mistakes students make when answering
this question? Some students might wrongly imagine that the reaction
was SN1, where the rate would be dependent only on the substrate,
with Rate = k[1-chlorobutane]. Others who are confused about substitution rate equations might mistakenly believe that the rate was
dependent only on the nucleophile, with Rate = k[sodium methoxide].
A third misconception (and the one with the most obvious mistake)
would be to imagine that the solvent had a role in the rate equation,
something like Rate = k[1-chlorobutane][DMSO].
By spotting the false leads and assumptions in answers (a), (b), and (d),
you can end up deducing that (c) is the correct answer.
a. Rate = k[sodium methoxide]
b. Rate = k[1-chlorobutane]
c. Rate = k[1-chlorobutane][sodium methoxide]
d. Rate = k[1-chlorobutane][DMSO]
Setting up questions like this one for friends, and having them do
the same for you, not only allows you to prepare for those standardized
exams, but also helps you succeed in the course.
a. b. c. or d. PHOTO:THINKSTOCK
FEATURE Mind over Matter continued