Monday, August 4, 2014

STUDY TIPS: General Chemistry

I’ve had the pleasure of working with several students in general chemistry this year.  It’s interesting to see chemistry through the eyes of my students.  General chemistry came easily to me as a student; as a tutor, I find myself asking, “When it comes to learning this material, what works?  What doesn’t?  What holes can we fill so that my students have an easier time with the exam?”

Here’s my list of study tips for general chemistry.  What you won’t find here: very basic tips like go to class, pay attention, take notes, work the problem sets.  I assume you know these things.  (But I’ll come back to that point about working the problem sets!)

* You must master the theory and application of chemistry concepts.  What do I mean by this?  Chemistry is a marriage of theoretical ideas, such as equilibrium, and the application of those ideas, such as calculating the equilibrium constant Keq value if I tell you the concentration of products and reactants in a solution at equilibrium.  A theory question might ask you to predict the direction of a reaction if the reaction quotient Q is less than Keq.  (Answer: the reaction will keep generating products until Q = Keq.)  (Pop quiz question: what’s the difference between Q and Keq?)

Many gen chem exams will mix together theoretical questions and math-based application questions.  You’ll want to be able to answer both.

“What if I don’t have practice questions for theoretical concepts?”  If you are lacking study materials, get in touch with me.  I’ve got a library of chemistry textbooks and practice exams to help you work on mastering gen chem theory.

* You must learn to think in four dimensions: the X, Y, and Z planes and time.  Chemistry takes place across all four of these dimensions.  Students who are, shall we say, spatially challenged (like myself) are going to have to focus their efforts on mastering three-dimensional chemistry.

A simple example from gen chem is molecular geometry: where do electron pairs (lone pairs or the shared pairs of a chemical bond) localize around an atom’s nucleus?  In other words, what is the three-dimensional shape that defines where the electrons are in space?  (Answer: it depends on how many of them we have around an atom.)

The question about time looms large when we start to talk about reaction kinetics.  This topic may be discussed in an abstract way, such as in spontaneous reactions that happen so slowly that they appear to be not spontaneous (such as combustion reactions that require energy, such as a spark, in order to begin), or we might talk specifically about reaction rates and rate constants.

* Work those practice problems, especially the practice exams.  Then practice some more.  It’s not enough to review your notes and think you understand the material.  Practice problems demand that you understand the material and are able to apply it to solve problems.

If I could offer one piece of advice to gen chem students, it would be to focus your study time on practice exams (assuming your instructor provides them to you).  Work as many of the problems as you can.  If you struggle through any problems, go back and work them again.  Try to see the logic that is applied to each problem so that when a similar problem shows up on your real exam, you know how to analyze it.

* Seek out additional learning materials.  I’m going to be really honest here: I dislike a lot of textbooks.  I hated my gen chem textbook in college.  If you find yourself in a similar position, don’t hesitate to seek out additional learning materials.  I’ve been using an awesome chemistry textbook in my tutoring that I can recommend: Chemistry (Third Edition) by Olmsted & Williams.

Also, this is the age of the internet!  There are so many wonderful on-line study materials (including this blog!).  I particularly like ChemWiki and MIT OpenCourseWare on youtube.  (As an aside, as much as I love Wikipedia, I don’t like it as much for studying chemistry.  And that’s okay.  The important thing is to find resources that work for you.)

* Make sure your algebra skills are strong.  A lot of problem-solving in gen chem comes down to setting up the problem as an algebra equation to be solved.  If you feel your algebra skills are weak, you might want to spend some time working on them either before you start gen chem or while you are in the class.  The more you can solve for X, the more comfortable you’ll be with chemistry problems.

* Learn to think about chemistry in terms of units. This tip comes from my partner, Tutor Paul, who has been tutoring engineering students for years.  When solving equations, we want units within a problem to match and cancel out.

One way to test your comfort with units is to do a little free word association.  What unit words come to mind when I say the following?

- energy?

- stoichiometry?

- pressure?

- volume?

- concentration?

For me, I have the following associations:

- energy? Joules.

- stoichiometry? Moles.  Or molar ratios.

- pressure? Atmospheres.

- volume? Liters.

- concentration? Moles per Liter.

My answers are standard units in which amounts are expressed.  A Joule is a unit of energy.  The stoichiometry of a reaction is expressed in moles (or molar ratios).  And so on.  Getting comfortable with gen chem means getting comfortable with units.

* * *

Readers, what else would you add to this list?  Tell me in the comments!

Happy studying!


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