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This page is to help answer the question of just HOW these labs are being
graded.
Class averages and yield averages are included.
Some grading schemes, such as Technique, are consistent across labs.
Others vary from lab to lab, depending on the task at hand.
 | GRADE
HISTOGRAM: TOTAL LABS 1-8, EXAM
1-3 |
| Lab #1 |
| Lab #2 |
| Lab #3 |
| Lab #4 |
| Lab #5 |
| Lab #6 |
| Lab #7 |
| Lab #8 |
| SPECIAL Lab #9 |
| EXAM #1 |
| EXAM #2 |
| EXAM #3 |
| Technique |
| Late work |
Lab #1, as the first lab, will be relatively lenient on
technique, pre-lab and yield/purity points. Nearly everyone was
assigned 11 or 12 in technique points; an 11 likely meant improper cleanup
(spills, lights on, equipment out), lack of prep, or staying past 12:10.
Notes:
*Points may need to be universally added or subtracted to create an 80% average.
CLASS
AVERAGES: Avg. technique -
11.6
Avg total lab - 79.2
Avg. yield Benzoic Acid - 36 ± 10
Avg. yield Acetanilide - 49 ± 14
RUBRIC:
20 - Technique: see Technique, below.
20 - Pre-lab (section 1-3)
Seriously, Be clear and concise!
Cite your sources!
7 - Intro. should be no longer than 1/4 the page
2 pts per experiment addressed, 1 - concise
8 - procedure should referenece sources (pg#, etc +1)
* assume reader is organic-lab literate
2 pts per experiment, 1 - concise
5 - table of reagents should include:
1 - Structures
3 - physical properties
(mp, bp, solubility, mol/L, color & appearance, etc.)
1 - Safety/hazard information
40 - Completed Report:
20 - Observations & Data
A majority of
points is from good and thorough bookkeeping:
4 -
appropriate use and propagation of significant figures
4 - Mel-temps: apparatus #, voltage(s), heating rate (ΊC/min), etc.
12 -
thorough observations, barometric pressure, etc.
20 - Results & Conclusions
4 - yield
4 - purity
4 - ID correct unknown
3 -
thermometer calibration curve
5 - Interpretation &
discussion, correctly accounting for errors
20 - Answers to questions:
20 - 4 questions complete, correct.
Lab #2 will have more points devoted to material yield and purity, as well as
concise, to-the-point writing. I will be much harsher on poor bookkeeping.
Notes:
* Don't leave pages out of the report. Please
please be careful on this. If you are worried that I may not have all your
lab pages, I can check for them during lab, no later than when your lab is
due. If you find a lost page after the lab is due, I can accept it at Late
Lab penalties; honestly, unless you left all your data and conclusions out of
the pile, it's less harm on your grade to just be more careful next lab..
* I am a big fan of CONTENT, not necessarily length. I also have to grade
12 rather long, not-always-legible lab reports, and having to hunt and search
for the important stuff is rough on these poor 23-year-old eyes.. Do keep
that in mind.
CLASS
AVERAGES: Avg. technique - 11.9
Avg. total lab - 81.3
Avg. extractions recovery
- 75 ± 12
Avg. trimyristin recovery
- 9 ± 3
RUBRIC:
NOTES: Being able to sensibly
distill your thoughts and knowledge into clear and consise writing is a very
important skill, and something I value highly in a lab report!
Make sure to check and include all
pages to your lab report when you hand it in. Having all your materials in order
is your responsibility!
Please keep sig figs in mind.
It may sound trivial to you, but it is ludicrous to recover .XX g of material
out of X.XX g, and have a percent yield of XX.XX%. Aside from precision,
it also gives you a good measure of acceptable error in your data collection.
20 - Technique
20 - Pre-lab (section 1-3)
2 - References for material (-1 for no page#).
8 - Intro (to-the-point!
+1)
6 - procedure
(brief +1, written for a chem-literate reader)
4 - table of
reagents (structure, properties, safety)
40 - Completed Report:
22 - Data/sample
15 - benzoic acid, 2-napthol,
napthalene (yields, purity)
7 -
trimyristin (yield, purity)
18 - Observations & conclusions
4 -
mel-temps (apparatus, V, ΊC/min, good values)
3 -
appropriate use of sig. figs
3 - Flow
chart for extractions
8 -
observation/discussions
20 - Answers to assigned questions:
8 -
flow chart (#13)
12 - #18 & 8
(6 pts. apiece)
CLASS
AVERAGES: Avg. technique
- 12.3
Avg. total lab - 80.2
Avg. cyclohexane in fract A
- 77 ± 5
Avg. toluene in fraction B - 98 ± 2
Avg. recovery of clove oil - 13 ± 3
(SHOULD be ~10-12 w/o ether)
* You should make sure to label all your GC traces and IR printouts!
* IRs should have peaks or sections labeled with appropriate groups.
* Hey now... I have also been hounding you about significant figures. You
should be including those in your writeups! If you are unclear about the
usesage/propagation of significant figures, please ask! It will save you
points in the future!
* ONly about half the students mentioned WHY fractional distillations are more
effective than simple distillations.
20 - Technique
20 - Pre-lab (section 1-3)
distill your thoughts into clear and consise writing!
I will not give full credit for
vague, roundabout,
or superfluous text!
AS NOTED IN THE MANUAL (pg.4), your intro should be a "brief introduction to the
experiment, and state clearly the purpose of it". Ideally (and according
to zubrick) your procedure should be ≤ Ό pg long. Even Dr. Mallory's
manual says no
longer than half a page. Keep my aging 23-year-old eyes in mind as you
assemble your Intros! Also, your procedure should really truly be brief!
8 - Heading & Intro (yes, to-the-point!)
2 - References (-1 for no page #)
6 - procedure
4 - complete table of
reagents
40 - Completed Report:
- Observations, Data, results, etc.
8 - 4 per GC separations, quality
(based on avgs)
2 -
good discussion, concise
DISTILLATION
6 - 3 per plot
& observations (T vs vol, smooth curve!)
3 - quality of separations
(fractional)
3 - WHY is
the fractional distillation bettter??
GAS CHROMATOGRAPHY
4 - pk calculation /
comparison with electronic.
2 - accurate assesment of
composition, discussion
CLOVE OIL & IR
5 - purity
and recovery (minimal ether)
5 - sensible
interpretation, predictions of impurity
(students lost a point for neglecting to mention
the out-of-place C=O peak, and attributing sources)
20 - Answers to questions:
20 - complete and correct (sig figs count!)
Lab #4 is a new format; I went pretty strictly, section by section, in
assigning points. Most people did very well and got all sections in there.
But neglecting a write-up section did cost points..
Notes:
<COMMON ERRORS>
not including procedures / drops counted for bayer & bromine tests
left out observed properties of products section.
left out or indicated incorrect limiting reagents.
no % yield given, or calculated incorrectly.
</COMMON ERRORS>
* Please write clearly and legibly, with info well-organized.
PLEEEEEASE organize your writeups so it is easy to read
and grade!!!
CLASS
AVERAGES: Avg. technique - 11.8
Avg. total lab - 80.3
Avg. yield dicholobutanes - 57 ±
16
Avg. yield methylcyclohexenes - 58 ± 8
Rubric:
20 - Technique (same as past 3 labs)
20 - Pre-lab (section 1-4) clear and consise writing!
2 - References (1 for no page #)
5 - Intro (to-the-point!)
6 - Reactions
& Mechanisms (Cl, dehyd, unsat-tests[mech.optional])
7 - Reagents:
2 - table of reactants (include physical properties!)
2 - limiting reagents
3 - products (incl. expected weight loss)
20 - Completed Report (section 5-10):
4 - theoretical
vs observed yields calculations.
4 - synopsis
of procedure, notes on experimental & results
3 - observed
properties of products
3 -
significant side reactions
(poly Cl, coupling; polymeriz'n; methylenecyclohexane optional)
2 - methods
of purification (statement or flowchart)
4 -
conclusions
20 - Spectral interprepations & Answers to Questions:
11 - Spectra &
Interpretations
4 - 2 GCs (correct labeling!)
3 - IR (labeled with -C-H, =C-H, -OH (if applicable),...)
4 - NMR (methyl and vinyl Hs comparison between A&B)
(1)- Bonus point for identifying "junk" in NMR of "A"
as methylenecyclohexane! Congratulations!
(NMR spec. provided in "things to keep in mind...")
9 - Questions
3 pts apiece, Complete & Correct
20 - Sample:
12 - *correct* yield/purity
4 - bromine
test (including controls)
4 - KMnO4
test (controls, too!)
Lab #5.
Notes:
<COMMON ERRORS>
not including procedures / drops counted for bayer & bromine tests
left out observed properties of products (appearance!)
left out STEREOCHEMISTRY, especially in assigned questions
left out limiting reagents
conclusion didn't include suggestions for improvement (i.e. actually
recrystallizing your material).
</COMMON ERRORS>
* Please write clearly and legibly, with info well-organized.
CLASS
AVERAGES: Avg. technique - 11.8
Avg. total lab - 81.0
Avg. yield hydrogenated diacid - 60% ±
19
Rubric:
20 - Technique (same as past 4 labs)
20 - Pre-lab (section 1-4) clear and consise writing!
2 - References (1 for no page #)
5 - Intro (to-the-point!)
6 - Reactions
& Mechanisms
7 - Reagents:
2 - table of reactants (include physical properties!)
2 - limiting reagents
2 - products
1 - structures (key reactants/products)
20 - Completed Report (section 5-10):
5 - theoretical
& obs. yields (WITH sample calculations)
5 - synopsis
of procedure, notes on experimental, results
3 - observed
properties of products
2 -
significant side reactions (include polym. diels w/ product)
2 - methods
of purification
3 -
conclusions
20 - Spectral interprepations & Answers to Questions:
8 - Spectra &
Interpretations
4 pts. each NMR & IR Q's 11&12. (complete & correct)
12 - Questions
4 pts. each, Q's 2,8,7 (complete & correct)
20 - Sample:
12 - yield & purity
(based on averages, mel temps, visual)
(-2 per sample not submitted, or only residue - I can't do a meltemp on just a
film of powder!)
4 - mel-temps
(apparatus, #Volts, heating rate)
2 - bromine
test (include # of drops until indicated result!)
2 - KMnO4
test (" ")
Lab #6.
Notes:
<COMMON ERRORS>
leaving out the boiling point of cyclohexanone
leaving out reactions for DNPH & semicarbazone derivs (mech. optional)
not calculating all % yields.
ignoring the clear presence of -OH peak in the IR.
</COMMON ERRORS>
* Please write clearly and legibly, with info well-organized.
* This ended up being a pretty bi-modal lab, as far as people including (or
failing to include) boiling point, yields, identification of the OH peak in the
IR, etc (extra points for identifying the equilibrium keto-enol tautomerization
that forms the OH peak in PURE cylcohexanone). As such, there tended
towards a cluster of grades in the mid-70s, and a cluster of grades in the
mid-80s.
CLASS
AVERAGES: Avg. technique - 12.0
Avg. total lab - 80.0
Avg. yield cyclohexanone - 50 %
± 13
Avg. yield semicarbazone - 52 % ± 6
Avg. yield DNPH product - 59 %
± 17
Rubric:
20 - Technique (same as past 5 labs)
20 - Pre-lab (section 1-4) clear and consise writing!
2 - References (1 for no page #)
5 - Intro (to-the-point!)
6 - Reactions
& Mechanisms (including derivatives)
7 - Reagents:
2 - table of reactants (include physical properties!)
2 - limiting reagents
2 - products
1 - structures (key reactants/products)
20 - Completed Report (section 5-10):
5 - theoretical
& obs. yields (WITH sample calculations)
5 - synopsis
of procedure, notes on experimental, results
3 - observed
properties of products
2 -
significant side reactions (include
2 - methods
of purification
3 -
conclusions
20 - Spectral interprepations & Answers to Questions:
12 - Spectra &
Interpretations
4 - IR, GC (correctly labeled!, no peaks bottoming out!)
4 - Comparison: cyclohexanone IR w/ pure cpd and alcohol,
4 - Discussion of the purity of cyclohexanone/cyclohexanol,
consistency of results.
8 - Questions
4 pts. each, #20a&b, #9
20 - Sample:
9 - Cyclohexanone (incl. b.p.
and yield)
4 -
semicarbazone
4 -
2,4-dinitrophenylhydrazone
(above 2 fields include mel-temps and yields)
3 - tests
(Chromic Acid)
Lab #6.
Notes:
<COMMON ERRORS>
left out observed properties of products
left out limiting reagents
left out sample calculations
% yield calculated from the wrong value, or weighed while wet.
</COMMON ERRORS>
* Please write clearly and legibly, with info well-organized.
CLASS
AVERAGES: Avg. technique - 12.0
Avg. total lab - 80.8 [→+2 adjust]
Avg. yield alcohol - 57 ±
18
Avg. yield acid - 62 ±
25
Avg. yield aldol - 42 ±
23
Rubric:
20 - Technique (same as past 5 labs)
20 - Pre-lab (section 1-4) clear and consise writing!
2 - References (1 for no page #)
5 - Intro (to-the-point!)
6 - Reactions
& Mechanisms (1 pt for including tests)
7 - Reagents:
2 - table of reactants (include physical properties!)
2 - limiting reagents
2 - table of products
1 - structures (key reactants/products)
20 - Completed Report (section 5-10):
3 - theoretical
& obs. yields (WITH sample calculations)
3 - synopsis
of procedure, notes on experimental & results
3 - observed
properties of products
2 -
significant side reactions (inclu. self-condensation)
2 - methods
of purification
4 - correct
ID of unknown & reasoning
3 -
conclusions
20 - Spectral interprepations & Answers to Questions:
12 - Spectra &
Interpretations
4 pts. each NMR & IR Q's 14, 15, 11. (complete & correct)
8 - Questions
3 pts. each, Q's 2, Q 14 from the manual
(number, reasoning, list of cpds)
2 pts. Q 3.
20 - Sample:
6 - 2 Canizarro
products yield/purity
(calculated appropriately)
4 - Aldol
product yield/purity
4 - Haloform
product yield/purity
6 - tests
(Chromic Acid, DNPH, Iodoform)
**2 points were added to all labs in the "Sample" section.**
Lab #8.
Notes:
<COMMON ERRORS>
did not calculate final 2-step total yield.
bromobenzene (NOT methyl benzoate) is a limiting reagent!!
did not calculate % recovery of Benzoic Acid.
did not include references.
</COMMON ERRORS>
CLASS
AVERAGES: Avg. technique - 12.8
Avg. total lab - 81.2
Avg. yield methyl benzoate - 67 ±
5
Avg. recovery benzoic acid - 2
Avg. yield triphenylmethanol
- 41 ± 13
Avg. two-step total yield -
28 ± 10
Rubric:
20 - Technique (same as past 6 labs)
20 - Pre-lab (section 1-4) clear and consise writing!
2 - References
5 - Intro
6 - Reactions
& Mechanisms
7 - Reagents:
2 - table of reactants
2 - limiting reagents
2 - products
1 - structures
20 - Completed Report (section 5-10):
4 - theoretical
& obs. yields
4 - synopsis
of procedure, notes on experimental & results
3 - observed
properties of products
3 -
significant side reactions (incl. rxn w/ water and coupling rxn!)
2 - methods
of purification
4 -
conclusions
20 - Spectral interprepations & Answers to Questions:
9 - Spectra &
Interpretations
5 pts. Q #10
4 pts. analysis, IR of Methyl Benzoate
11 - Questions
3 pts. Q #6
4 pts. each, Q's #7 & 7
20 - Sample:
4 - Methyl
Benzoate yield & purity
3 - Benzoic
Acid % recovery, agreement /w methyl benzoate yield
6 - Triphenyl
methanol yield & purity
4 - overall
two-step yield.
3 - molec.
sieves? :\
20 out of your 100 points per lab report will be for "technique".
An average grade is 12/20.
If you get a 12, don't fret; it means that
you didn't do anything WRONG, but you could improve through more thorough
preparation, efficiency, and better yields.
AS STUDENT SKILL INCREASES, SO DOES THE EXPECTATION FOR WHAT AN "AVERAGE" LAB
PERFORMANCE ENTAILS!
20 (~12)- "technique"
8(~5)- SKILL & UNDERSTANDING (almost impossible to get a perfect score on this, because skill is very much a thing learned while in lab, but Zubrick is very helpful in developing this; also, there are some questions you really SHOULDN'T need to ask, and many questions from me you should be able to answer)
6(~3)- PREPARATION & EFFICIENCY (do you know what you're doing? how well prepared ARE you? good and intelligent use of time, quick but never sloppy; due to recurring issues in a previous semester, staying past 12:15 will now receive a straight 5-point deduction here!)
6(~4)- SAFETY (goggles? gloves? apron? aware of others? common sense? as a dirty bench represents a hazard to self and others, clean-up is also included here.)
A highest mark in any of these categories implies "perfect"; in
reality, nobody's perfect, and I will seldom if ever give out a perfect score.
In addition, these items can add or subtract points off the top; I will never remove more than the maximum for any of these categories:
Start over: up to -4 (depending on severity)
Broken glassware: up to -3 (depending on reason, and severity)
Creativity (a particularly ingenious approach to solving
a problem can get you back up to +2 lost points)
Late pre-lab: -15 points flat (have them done BEFORE
class!)*
Late Report: -5 points for up to a day
-10 points for up to 1 week
-20 points for up to 2 weeks
-30 points for up to 3 weeks , etc.
Additional notice on "partial" labs:
If you neglected to turn in a few pages of your lab on the day it was
due, REGARDLESS of whether you had it done ON the due date, that portion of the
lab is either missing, OR the whole lab is late. That is because I
will have to go back and re-grade your material, and it's easier on both of us
for you to just learn from the setback and do a quality job on your next lab
report.
So.. unless that portion left out was crucial (i.e. worth >10 points,
or a few pages-worth), I'd chill and not bother with turning in a late lab page.
Please. I'm being strict on EVERYBODY, not just you. Don't
fight it!
Exams are out of 150 points, and tend to average approx. 80%
CLASS
AVERAGES: Whole class - 127
This section - 124
This exam had a surprisingly high average across all sections, and most
students of this section improved by at least 10 to 20 points!
Congratulations!
CLASS
AVERAGES: Whole class - 133
This section - 132
Well done! ^_^
CLASS
AVERAGES: Whole class - 116
This section - 117
