Old Exam 1A

Old Exam 1A - ANSWER KEY Seat - Chemistry 241 Exam 1 March...

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Unformatted text preview: ANSWER KEY Seat - Chemistry 241 Exam 1 March 3, 2009 Honor Pledge: I have neither given nor received help on this exam, nor have I seen anyone else do so. Signed:__________________________________ 1. 2. 3. 4. 5. 6. 7. 8. 9. Total _________ 15 10 10 10 10 10 8 15 12 100 SHOW YOUR WORK CIRCLE NUMERICAL ANSWERS 1.(15 pts The dead time of a GC column is 1.0 min. The retention times for analytes X, Y and Z are 12.0, 13.0, and 15.0 min, respectively a) what is the capacity factor for X? t t- t = k m m r ′ =- = . 1 . 1 12 11 b) what is the ratio of the time Z spends in the stationary phase to the time spent on the column? t s /t r = 14.0/15.0 = 0.933 c) What is the partition coefficient for Z if V S = 0.5V M ? V V K = t t m s m s = = = ) . 1 ( 5 . ) 14 ( V V t V t V K m m m s s m 28 2.(10 pts) If a 15 cm long column has a plate height of 15 μ m what is the half-width of a peak that elutes in 9.5 minutes? N L = H = × − 6 10 15 15 . H L = N 1.0x10 4 2 2 1 2 r 2 2 r w t 5.55 = w t 16 = N 4 2 2 2 1 10 . 1 ) 5 . 9 ( × = 5.55 N t 5.55 = w 2 r W = 2.2x10-1 min 3.(10 pts) For a capillary electrophoresis system using 27,000 V applied across a 62 cm column, the electroosmotic 3....
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This note was uploaded on 01/09/2011 for the course CHEM 241 taught by Professor Tiani during the Summer '08 term at UNC.

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Old Exam 1A - ANSWER KEY Seat - Chemistry 241 Exam 1 March...

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