Final Exam & Grading Schedule

Transcription

1 1/07/01 Physical Chemistry Lab Chem343 Lecture 7 (1/07/1) Class Schedule/Grading Final Review Final Exam & Grading Schedule Final Exam Schedule Dec 13 (Thr) From 1 PM (hours) at 130 SES; ~60 % is multiple choice questions Your TA will send the grade (Final & Overall) by the end of Dec 13 by e mail. If you need any corrections, please claim it before Dec 14 at 3 pm. We will return your graded notebook on the day of the Final. We will not return the Final or Quiz 4, but let you review them in case that your grade is very close to the border line. All other grades are final. Quiz 4 (Today): All the 6 experiments + lecture 1

2 1/07/01 Final Exam 6 Experiments + Lecture materials multiple choice questions (60 70%) 6 calculation or long questions hours NMR Review the class materials on NMR from the lectures (Lectures, 3) Review the NMR presentation Principle of NMR (Spin magnetic moment, Transition energy, Frequency) 13 C signal assignments, 1 H signal assignments DEPT HETCOR & COSY The principle of molecular diffusion Long questions are probably on signal assignments for amino acid(s) or small compounds. For Long questions, I may ask you to draw a possible NMR spectrum for a compound. Check out the structures of amino acids and possible chemical shifts.

3 1/07/01 Zeeman Interaction Spin in a Magnetic Field When a spin is placed in a magnetic field, the energy is given by E m = μ Z B 0 = γmħbħ 0 1 Figure 1. Zeeman energy levels for spins of I =1/ and 1. Lower energy level attracts more spin population. It induces spin polarization (bulk magnetic moment) 4 C ~ H NMR Frequency The transition energy between the two states is E = γħb 0. NMRf frequency is easily obtained as 0 = E/h = B[Q1] 0 γ/π. 1 4 C ~ H The frequency is typically in a range of MHz RF (Radio Frequency) 3

4 1/07/01 Induction Effects in 1 H shifts 1 H chemical shifts of CH n Cl 4 n (ppm) CH e - CH 3 Cl 3.05 CH 3 Cl CH Cl 5.3 CHCl H shifts of CH 3 X (ppm) Less e -, Less Shielded F OH NH H Me 3 Si TMS Example 13 C and 1 H NMR spectrum spectra of diethyl ether (CH 3 CH ) O (CH 3 CH ) O Q. Which is C 1 H? Quartet Triplet 4

5 1/07/01 Miller plane & index Q. What is the Miller index below? b a b a (1,) (,1) Gas Effusion Theory Questions What is an ideal gas? Negligible volume compared to gas line Elastic Collisions = Kinetic Energy remains constant What are the differences between effusion and diffusion? Pressure Mean free path What is the main factor which affects the mean free path? Pressure Factors that influence average speed / probability density(m B Distribution) 5

6 1/07/01 Experimental Questions Why is the diffusion pump important? Mean free path Back Effusion What type of gas can be monitored by gas effusion? Non toxic and non flammable gases (No cold trap on the pump) p) Molecule size smaller than pinhole Constants Area, Molar Mass, Gas Constant, and Volume Calculation Questions Calculate the increase/decrease in speed if the temperature t or molar mass increases/decreases Any calculations from the lab Appropiate Equations will be given 6

7 1/07/01 CHEM 343_F1_FTIR questions for final_examples Q1: Consider the following analytes and answer which would absorb in IR frequency range (Y/N): A: Phenol B: Water C: CH Cl D: CO E: O a.c and E b.only E c.a, B and D d.none of the above Q: Consider the following analytes and answer which would show a FINE ROTATIONAL STRUCTURE in its FTIR absorption spectra (assume analyzed molecules are polar): A: Solution of Cholesterol in HCCl 3 /CH Cl B: Pulverized solid PVC paletted with KBr C: Air sample containing gaseous contaminants D: Aqueous peptide solution E: gaseous pyrolisis products a.a and B b.only D c.c and E d.all of the above CHEM 343_F1_FTIR questions for final_examples Q3: Consider following statements related to FTIR spectroscopy and choose an answer that applies: A: Heavier the atoms in a diatomic molecule are, smaller the vibrational wavenumber is B: Energy of rotational levels is usually ~ 10 3 times smaller than that of the corresponding vibrational levels C: Value of rotational constant is dependent on the vibrational energy level D: According to anharmonic oscillator potential energy curve it takes much more energy to move atoms closer together that it takes to move them apart a) A is the only one correct b) All are correct but C c) All are correct Q4: Considering a model of a rigid rotor choose an answer that best describes given symbol or term: A) DJ ( J 1) a) Term for transition energies in P-branch b) Term for vibrational-rotational interaction constant c) Term expressing contribution of centrifugal distortion B) Term for moment of Inertia T T ( v, J ) final T (v, J ) a) b) I=µr c) F( J ) BJ ( J 1) initial 7

8 1/07/01 CHEM 343_F1_FTIR questions for final_examples Q5: FTIR absorption spectrum for DCl with labeled R and P branches with initial state J values is shown below. Which statement(s) is/are correct: A B a) In case A: J initial is equal 1 b) In case B: J final equals 0 c) In case B peak due to D 37 Cl is observed d) In case A peak due to D 35 Cl is observed e) a and b f) c and d g) none of the above Q6: The IR spectrum of 1 C 16 O shows vibrational absorption band centered at 170cm -1. At what wavenumber would the corresponding peak for 14 C 16 O occur? Use: Ar( 1 C)=1; Ar( 14 C)=14.003; Ar( 16 O)= M M M 1 1 M ~, ~ , CO CO 1 CO 14 CO 1/ Final Exam Preparation On Nano Diffraction 1. [Theory]: Explain the Bragg equation and deduce the question based on the used model for D and 3D dimensions.. [Sample]: Lattice system of the crystal in the experiment and parameter comparison of each sample(d or D). 3. [Experiment set up]:wavelength of the laser; dos and don ts for better data. 4. [Diffraction pattern]: Difference and reasons for multiple domain and single domain. 5. [Calculation]: How to calculate the d spacing based on the known factors. Establish relationship between D and d based on each structure. 6. [Miller indices]: Simple models. 8

9 1/07/01 Examples: Photophysics and Molecular Spectroscopy Review Brian K. Yoo December 7, 01 9

10 1/07/01 Jablonski Diagram ed/quantum/graphics/jablon.gif What is the basis for the observed Stoke s shift? Why do we expect to see a mirror images for the excitation and emission profiles? Know numerical calculations, basis and meaning of variables, i.e. Beer Lambert Law, Henderson Hasselbalch What are the differences between fluorescence and UV, vis spectroscopy (absorbance)? 10

11 1/07/01 Error Propagation Example V m V n RT, T C, P atm P T(K) T( C) C K T(K) 0.00 C K T(K) K L atm V m K mol K atm V m.41 L mol -1 Error Propagation cont. Vm Vm V m R V m T V m V V m T V m R T,V T R,V V R,T T V V T R T RT V V V L atm Vm K mol 0.08 K atm L atm K mol K atm atm Vm 0.1 L mol -1 V m L mol -1 V 11

12 1/07/01 final presentation Chemistry 343 Fall 01 THEORY Reactive electrones The total electronic spin angular momentum is S+1 S for S0 is 0 (1/-1/) = singlet Flouroscence X Phosphoroscence: Liquid N T RT 1

13 1/07/01 REACTION - Isopropanol (take H) - Protonated ketyl radicals Benzoph. + Isoprop. - Basic - Deprotonated ketyl radicals - Dimerization Benzopinacol NaOH + HO Fixed wavelength 13

14 1/07/01 CALCULATION K obs =slope*el (e:5000 /M.cm, l: 5 cm) K obs = k7 x [H] / k6 [H] = 10 -ph 14