exp 6 calculations

[robert zellmer]

I'm getting some questions about the calc. for exp 6.
First of all you may want to wait until after tomorrow, Thursday,
to start these as we will be covering much of this material
tomorrow.

The manual and rubric states to show calc. for all types of
calculations performed.

1) For Parts A, B and C that means you should show one
delta(T) sample calculation for one part (Part A is fine).

2) The calculations for *ALL *the *q values *leading up to the
final "q" which you will be reporting in parts A, B and C.

For part A you need to show the eqns and q values for the
calculation of the heat capacity for the cup.  These are shown
on pages 38-39 in the manual.

In parts B and C there are calculations for moles which should be
shown and limiting reagent in Part B.  Also, for parts B and C show
all calculations involved in determining the heat evolved by the
reaction (Part B eqns are shown on pages 39-40 and part C are on
page 40) and the calc. for the delta H values in both parts.

For part D you're using Hess's Law as explained in the manual,
the book and my notes.  You need to show how you manipulated
each eqn and the delta H values and add them up to get delta(H3)
and delta(H4).  This means you need to write each reaction equation
used and show how you get the corresponding delta(H) for
this manipulated eqn. and then how the eqns add up to give the
desired eqn and how the delta(H) values add up.   You'll be using the
reaction eqns and delta(H) values you get in parts B and C along with
reactions 3 and 4 on page 40.

Remember to look at my finished graph for exp 6 to see what your
graphs should look like.  You can insert the best-fit lines and
time-of-addition line using the tools in Excel (got to "Insert" and then
"Shapes").  These lines can be manipulated quite easily and you can
get pretty good best-fit lines, undoubtedly better than what you can
draw by hand with a ruler.  Make sure they extend the lines and cross
the time-of-addition line so you can find T_i and T_f.  You can also insert
text boxes for the T_i and T_f and time-of-addition labels. It's really
fairly easy to figure out how to draw lines in Excel or textboxes for the
T_i, T_f and "time of addition"labels . You'll need lots of grid lines
since you'll need to read T_i and T_f off the graph.

If you can't figure out how to draw the lines in Excel, you can print
the graphs out and draw in the best-fit lines and time-of-addition line
by hand (using a straight edge, like a ruler).  You can write the labels
for T_i, T_f and time-of-addition by hand.

If you decide to do the whole graph by hand you must get proper
graph paper with lots of grid lines (the lab notebook paper isn't
good enough).

Of course in the last two cases the graphs will then have to be scanned
and included in the report file.

I really encourage you to do this in Excel and learn how to draw the
lines in using the drawing tools in Excel.  This is the preferred method.

Dr. Zellmer
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