There are a few changes for this experiment.
You can find these by going to the "Laboratory"
link on the class web page (not Carmen).


1) On the report sheet on page 9 you should have
   the water temp at the top.  The next line is
   the calculated density of water at this temp
   using the eqn. just below.  This eqn was obtained
   by someone fitting the density obtained in lab
   at various temperatures between 20 and 30 Celsius.

   In the data table you are supposed to calc. and
   record the measured density for each set of mass/volume
   data.  The "actual" density is the number from above.
   It will be the same all the way down, unless you took
   the temperature multiple times (for each piece of
   glassware or each measurement).

   Technically, you should take the temp of the water
   each time you use it for a piece of glassware.
   You aren't told to do this and thus are assuming
   the temp of the water is the same throughout the
   experiment.

2) I get a lot of questions about the graphing

   The graphs have nothing directly to do with the table.
   You will be making 4 graphs, one for each piece of
   volumetric glassware.  You should graph mass (y) vs.
   volume (x).  Make sure you use the whole piece of paper
   and spread the data out (good use of the axis) so it
   takes up most of the space of the graph.  Don't make
   the labels and titles huge (use 10 or 12 point font).
   Everyone should have received an example of good graphs
   in lab.  Even these graphs don't take up the full page
   since I had to shrink things so I could write on them.
   The 2nd graph shows an example when you have more than
   one set of data plotted.  You can bring the legend inside
   the graph area to allow the graph to spread out and occupy
   the whole page.  You don't need a legend when there's only
   one set of data plotted (as for each graph in exp 1).  You
   do NOT need grid lines for these graphs for exp 1.  The
   default orientation is Landscape and that generally is the
   best for graphs.  Later for exp 6 you'll see that Portrait
   mode is the proper orientation.

   There's also a link you can use to help get you started
   with Excel if you've never used it before.  It's a simple
   example for a density graph.  This is similar to what you
   are doing in exp 1 but not exactly the same.  Go to the
   following link and you will find this, along with other
   useful links.

   http://chemistry.osu.edu/~rzellmer/excel/excel.htm

   Many of my examples use an older version of Excel (Excel 2003).
   I have a link explaining the major differences between it and
   the newer versions.  Again, click tabs, right-click, etc. and
   explore what it can do and where to find things.

   Remember, 1 graph per page.  It should occupy the whole page,
   which means there should be very little space between the
   edges of the graph and paper.  The data points should occupy
   the vast majority of the space on the graph (a bare minimum of
   empty space between the points and the edges of the graph).

I get questions about what R^2 is and how this relates to the
report questions.  Students often wonder how the graph relates
to determinate and and indeterminate errors, accuracy and precision.
Here's some help and questions to make you think.

1) What is R^2.  This is called the "correlation coefficient"
   (at least in Excel).  This is one measure of how good the
   curve chosen fits the points.  Generally, the closer R^2
   is to "1" the better the fit.  However, R^2 isn't the only
   indicator about the "goodness" of the fit and can be misleading
   unless you pretty much know what type of curve the data should
   fit (i.e. in exp 1 we know the curve should be linear).  You can
   actually get an R^2 close to "1" when fitting a portion of a
   parabola to a straight line fit.

   For exp 1 we know the relationship between mass and volume is
   linear (mass = (density)(volume) + intercept).  The closer the
   points are to the line the less the random error in the data
   and the better the precision.  Is this type of error determinate
   or indeterminate?

2) What should the intercept be?  Did you get this intercept?
   What could cause you to not get the correct intercept (determinate
   or indeterminate error)?  Is this related to precision or accuracy?
   Think about what it means if the whole line is shifted up or down
   so you don't get the correct intercept.

3) How does the % error in the table relate to accuracy or precision?
   What does it mean if the % error is small?  Is this relate to
   precision or accuracy?  What does it mean if the % error in each
   of the four measurements for a particular piece of glassware
   are really close to each other?