[CHM 112] Lab Graphs

[Andrew J. Pounds]

Class, I spent a lot of time grading yesterday.  During that time I had 
a chance to look over the graphs you submitted in your last lab report.  
Graphs are an important TOOL in scientific analysis and deserve the time 
to be prepared well.   In the upcoming labs I will be paying a lot of 
attention to your graphs.  Here are some pointers.

 1. Each graph should be either COMPLETELY computer generated or
    COMPLETELY drawn by hand.  Since you all told me in class on
    Wednesday that you had access to Excel, I am expecting that the
    graphs are completely computer generated and that all of the
    components on the graph will be drawn by the computer.  Don't get me
    wrong, hand drawn graphs are a beautiful thing.  Come visit me in
    Willet and I'll show you examples in some of my books.   But think
    about this.   If you draw part of a graph with the computer and then
    fill in the missing components with a hand drawn line or axis labels
    you are conveying to the reader that you are really incompetent. 
    You are now in college and many of you are preparing for a
    professional careers in medicine, engineering, or the sciences. 
    It's time to step up your game and start producing professional
    looking graphs.  If you need help - ask!
 2. Each of your graphs should be on a page by itself.  In rare
    instances I will tell you to combine graphs on a page, but in
    general each graph should be on its own page and should take up the
    entire sheet of paper.  It's terrible to get an 8.5x11 sheet of
    paper with a 2x2 inch graph in the upper left hand corner.   I
    prefer that your graphs be in LANDSCAPE format and take up the
    entire sheet of paper.  Again, Excel will allow you to do this.  If
    you need help - ask!
 3. Both the X and Y axes should be labelled with units.  In  this case
    you first graphis Y axis will be "ln(rate)  M/s" and your X axis
    will be "ln([I^- ]) (M)"
 4. Your data POINTS should be plotted as POINTS (or some other
    symbol).  There should be NO LINE CONNECTING THEM.  If necessary,
    change the automatically generated legend label (Generally it's
    somthing like Series 1) to a more meaningful label.
 5. In this graph you do need to plot the best fit line through the data
    points and also place the equation of the best fit line somewhere on
    the plot.  Excel calls this a "Trend Line" and you will find a
    tutorial on how to plot trend lines in Excel in the Lab section of
    the class web page.  While the tutorial is somewhat dated, the basic
    ideas still work in newer editions of Excel.  If you can't figure
    out how to do this -- then ask!  I will be checking to see if the
    slope from your best fit line agrees with what you record on your
    report sheet.
 6. Take a final look at your graph, if it needs a title, add one.  If
    you need to clean up the data labels so that they make more sense,
    do so.   Do any final formatting to make the graph look professional
    and clean.
 7. Print it!


Please let me know if you have any questions!

-- 
Andrew J. Pounds, Ph.D.  (pounds at theochem.mercer.edu)
Associate Professor of Chemistry and Computer Science
Mercer University,  Macon, GA 31207   (478) 301-5627

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