exp 16: general help and data-entry pre-lab

[robert zellmer]

I'm getting questions about exp 16 and the pre-lab.  We
weren't able to get to freezing point depression in section
13.5.  The manual has a discussion with everything you
need for the lab and pre-lab.

If you took 1250 previously exp 16 has changed slightly.  The
volume of the solvent (cyclohexane) has changed and the masses
of solute added (and total mass) in each trial have changed.
The Data Analysis section of the manual still uses 20.00 mL of
cyclohexane in the example on page 102.  The new volume is
10.00 mL.

Look a the "Laboratory" link on my class web page for additional
help for exp 16.  Do this before lab, while writing up your procedure
and before doing the pre-lab.

You will need to collect some temperature data which will not
wind up on the report sheet.  Make allowances for this in your
notebook.  You need to do at least 3 f.p. "determinations" for each
f.p. you see on the report sheet.  You may have to do more than
3 f.p. determinations.  You do them until you get 3 f.p. w/in 0.1 degC
of each other (e.g. 6.1, 6.3, 6.2).  Then you take the average of these
three.  Report your answer to ONE decimal place (you can't gain a
s.f. when averaging only three numbers).

There is a data-entry pre-lab.  You won't understand what you
are supposed to do with the numbers given if you don't carefully
read the manual and write the procedure first.

Reminder, for the on-line data entry you really need to do it in one
sitting.  When you don't we can't guarantee what will happen.
Don't walk away since it could time out and if it does it will start
over from the beginning.  Also, if you do it by clicking the link
in Carmen your time limits will be based on those of Carmen.
You are better off clicking on the links in the syllabus.  Even so,
don't plan on getting an unlimited amount of time to work on these
and not get timed out by the server.

Read the directions.  I'm finding a number of people didn't for
exp 14 pre and post-lab.  There's an "Instructions" button
in the top left-hand corner on the page.  Click on the "policies
and procedures" link at the bottom of the page before starting.
I sent this as well in a previous link.

Also, if you have problems please send me ALL the information I've asked
for in a couple of previous e-mails.  Also, take a picture or do a 
screen capture
and send these as well.

Dr. Zellmer
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