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OutlineGo over syllabusIntroduction to lab sectionStart chapter 10Discuss chapter 10 project
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Lab overview Held on Wednesdays (typically the last 2-3 hours of
class) Lab attendance is mandatory and there are no make up
labs◦ Please contact me if you miss a lab due to illness or some
other emergency. We can work something out but it will not be for full credit since part of the credit is actually doing the lab
Things to consider◦ Most of the labs take about 90 minutes◦ While a few do require more time, it will take more time if you
do not come prepared◦ Patience and attention to detail will help you do well in the lab
There are 8 graded labs, each consisting of . . .◦ Preparation (prelab) work◦ Lab work◦ Postlab work
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PrelabGrading prep work
◦ I will have a checklist and check your notebook at the start of class
◦Necessary information should be filled out before class begins and must be signed off by the instructor before you start working (more on this later)
◦ If I see you doing pre-lab work in lab (i.e. not done before you get here) you will not get credit
Do not start early◦The first 5-10 minutes are for me to provide
useful hints and information◦ If you’re setting up, you’re not paying attention
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During labNo food or drinks, everPersonal items should be stored underneath
bench-topsProtective eyewear should be worn at all
times until everyone is done (or I say so)◦ Wearing them on your neck, on your forehead, on
your hair, or putting them on the bench does not count as wearing them
◦ They may be uncomfortable, leave marks, and look funny, but the alternative is blindness. So keep…them…on!
One reminder is all I will give. After that, you will lose points each time I see it
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Postlab You are welcome (and I encourage you) to stay when
you are done◦ Work on calculations
Calculations should always include correct significant figures and units
You need to show one sample for each different type of calculation If you repeat a calculation two or three times you do not need to
show the work for every individual calculation (unless you want to)
◦ Ask questions◦ Check answers
Before you leave, show me your notebook (~5 points)◦ I will have a checklist and check your notebook at the end of
class◦ Coming back after class does not count because I don’t
know if you actually did it or just copied it◦ Necessary information should be filled out before leaving
(i.e. calculations, tables and figures)
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GradingThe lab section is worth 120 out
of the total 460 points for the class (~25%)◦Lab work
80 points 10 points per lab
◦Lab reports 40 points 5 points per report
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Lab work grade breakdown Prelab (~5 points)
◦ Name/date/lab name◦ Answers to pre-lab questions (if any)◦ Purpose or objective of the lab◦ Summary of the procedures (at least one high quality
paragraph outlining the lab) During lab
◦ Points will be deducted for not following safety rules and lab practices (e.g. -2 points for not wearing proper attire)
Post lab (~5 points)◦ Notebooks will be checked for the following:
Sig figs and units Completed data tables Calculations (show work for credit) Completed postlab questions
◦ Points will be deducted for not cleaning your bench or shared workspaces
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Lab report grade breakdownLab reports are due at the next lab
meeting (typically one week)They are due at the start of classOne lab report per group 5 points per report
◦1 point for the Abstract◦1 point for the Introduction & Methods
sections◦1 point for the Results section◦1 point for the Discussion section◦1 point for overall report
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More on the lab notebook:General informationYou may use any notebook you like (carbon
pages are not required) as long as it is◦ Dedicated to lab (not in your normal note-taking
notebooks)◦ Bound (absolutely no loose pages)
If it meets the above specifications, feel free to use the same notebook you used in CHEM161
The notebook is your record of what you did and what you observed
Never, ever, ever write anything on scrap paper or the lab handouts. Everything goes into the notebook
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More on lab notebook:Procedure summary This prelab component not only helps you prepare for
the lab, but also gives you a head start on the methods section of your lab report
Sample full credit procedure summary (shows you read and understand the lab):
“In this lab we will do four different acid-base titrations: strong/strong, strong acid/weak base, strong base/weak acid, and weak/weak. First, we will set up the titration apparatus and prepare the LabPros to collect titration data. Next, we will measure the volume of an individual drop from the burette. Finally, we will carry out the four titrations using different combinations of acids and bases and record the titration curves using the LabPro. After the titrations are done, we will dispose of the waste products in the appropriate container.”
Sample zero credit summary:“We will do lots of different titrations.”
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Precision vs Accuracy Precision
◦ reproducibility or repeatability Accuracy
◦ degree of closeness of a measured value to its actual value (i.e. getting the “right” answer)
Data may be◦ Precise, but not accurate (good, not great)◦ Precise and accurate (best)◦ Not precise and not accurate (worst)
In general, precision is more important than accuracy◦ Accuracy problems can be fixed (calibrations, changes to
method, etc)◦ Precision problems can be difficult to track down and fix
