Class admin
• Turn in revision exercise #2
• Pick up and fill out TA evaluation forms
– Pink = Adrienne
– White = Khadine
Oxygen uptake by Co(salen)
• Notes on part 2 of lab:
– Bring stopwatch
– Depending on yields, may carry out project as a group
Last week: prepared Co(salen)
• Co(salen) can bind oxygen, just like the
biological heme molecule
O
NH2 + 2
H2N
en
OH
sal
easy
N
N
OH HO
salenH2
HO
O
O
Co(II)
hard
N
N
Co
O
HO
O
N
versus
N
Fe
N
N
N
Co
2+
O
O
N
Co(salen)
Co(salen
Ferrous Heme
Oxygen binding depends on Co environment
• In crystals:
N
N
Co
O
O
O
O
Co
N
N
Active structure
Sol
• Solvated:
N
N
Co
O
O
O
O O O
Co
N
N
N
N
Co
O
O
O
O
Co
N
N
Mercury view
Inactive structure
Sol
N
N
Co
O
O
O
O
Sol
2:1 structure
1:1 structure
• Co(salen) exists with Co in a 4, 5, or 6 coordinate site
• Solvated Co(salen) will bind O2 when it is 5 or 6 coordinate
Experimental apparatus
graduated
pipette
stopper
vac. flask
DMSO in tt
tubing
water
Co(salen)
Which way will the water move?
How many SF’s to report?
Graphing data
• What is our:
dependent variable
independent variable
• Which one belongs on which axis?
• How do we best extrapolate to infinite time?
Revision exercise #2
• Goal: submit an improved version of your lab 6 (MIMT) report
– Take your report to the University Writing Center for feedback in paper and
electronic form [computers available there]
– You can skip the “Questions” section in your re-write – please focus on the
report text (Title, Introduction, Data Analysis, Discussion)
– Turn in your original and revised lab reports to me, with UWC comments if
they are available
– Due date: Class period on April 30th (two weeks from today)
Note: no other lab report is due that week
• Hours for University Writing Center:
– Mon-Wed: 10 AM – 10 PM
– Thur:
10 AM – 7 PM
– Sun:
2 PM – 7 PM
• Web site: http://writingprogram.hfa.umass.edu/writingcenter/writingcenter.asp
• Located in the Learning Commons of the WE DuBois Library
Writing exercise
• Experimental assignment
• Communication error
– My intent: spend extra time revising the writing
(conciseness, organization, flow, transitions, paragraph
divisions, grammar, readability, style)
– Student interpretation:
GRAMMAR
• Grading – positive points
– Will reward effort
– Will reward accomplishment
Evaluation of writing in course
•
How useful were the lectures on writing
Extremely
•
Very
Reasonably
Somewhat Not at all
Very
Reasonably
Somewhat Not at all
How useful were the UWC comments on writing the lab reports
Extremely
•
Somewhat Not at all
How useful were the instructor comments on lab report 5
Extremely
•
Reasonably
How useful were the TA comments on writing on the lab reports
Extremely
•
Very
Very
Reasonably
Somewhat Not at all
Comments for improvement on the writing aspects of Chem242
NA exercise
• 25 pts / problem
-10 if SF errors
-5 unit errors
• 25 pts for group work (consistency in answers)
• Positive points only.
(Divide points by 10, score will be added to lab 8 grade)
Experimental
• Recrystallization
–
–
–
–
Solvent temperature – entropic arguments
Evaporation – effect on purity?
Solvent choice (high relative solubility for impurities)
Recrystallization should be done relatively slowly
• Anaerobic environment
– vacuum
– pump / fill cycles
Coordination of metals in inorganic compounds
HO
HO
O
N
N
Fe
O
N
N
N
Co
2+
O
O
N
Co(salen)
Ferrous Heme
Sol
N
N
Co
O
O
O
O O O
Co
N
N
Sol
N
N
Co
O
O
O
O
“dentate”
Sol
2:1 structure
Coordination
Number
1:1 structure