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

[Zellmer, Robert]

I'm getting questions about exp 16 and the pre-lab.  We
discussed freezing point depression in lecture on Tue..  The
manual has a discussion with everything you need for the lab
and pre-lab.  Of course you can watch the lecture videos in
Carmen covering this material.

Read the Data Analysis section in the manual.  It covers what
you'll be doing and what volume of cyclohexane (solvent) should
be used.  Note, you should be using 10.00 mL of cyclohexane.
Record the actual amount you use in the lab.  It doesn't need to
be exactly 10.00 mL but should be at LEAST 10.00 mL, i.e. 9.99
wouldn't be correct but 10.01, 10.02, etc. are okay.  Why?  You
have 4 s.f. for the volume while 9.99 mL has only 3 s.f.  Just don't
make it much more than 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.

When doing the experiment in lab, you will collect some temperature
data which will not wind up on the report sheet.  You will do at least
3 f.p. "determinations" for each f.p. you see on the report sheet.
Many people wind up doing 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.  You will see data
like this in the data sets on Carmen.  Report your average f.p. 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 often find a number of people who don't do
this before doing the pre or post labs.  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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