INFRARED SPECTROSCOPY 2

pdf

School

Texas A&M University *

*We aren’t endorsed by this school

Course

237

Subject

Chemistry

Date

Oct 30, 2023

Type

pdf

Pages

Uploaded by BaronIron10780

e A T T T e —— |/ | I INFRARED SPECTROSCOPY Name JUH]1ENNe Penarloy pate (0Q [ 25/23 TA. K ate Monheim Room Color WORKSHEET Open the IR Tutor program. Initially, a screen will open telling you to change your monitor resolu- tion. DO NOT change the screen resolution, just hit continue! Once you have opened the IR Tutor program, use the program to answer the following questions. Each question can be answered with the information found in the program. 1. Whereis the IR region relative to visible light? @ near the red b. near the violet 2. How did Hershel first detect IR light? pointing a prism 3. Isall infrared light the same wavelength? N O 4. What does A stand for? wavelength 5. What does v stand for? Lrequency 6. What does v(bar) stand for? wavenumpey 7. Write an equation that relates energy (E) to wavelength. E=hc/M 8. From your equation, what happens to energy as the wavelength increases? eheraq M i€y decredse 9. Write an equation that relates energy and wavenumbers. 10. From this new equation, what happens to wavenumbers as energy increases? incregie 97 NOT FOR DISTRIBUTION - FOR INSTRUCTORS USE ONLY . T

% WRITE-UP 11. What range of wavenumbers represents the mid IR region? 4000~ ypocm™! 12. Why are lenses not used in IR instruments? Lenses absorb lignt 13. Which type of IR instrument measures all wavelengths of IR at once? 2. Classical @)mn‘er Transform 14. What happens to the potential energy of a spring if it is stretched from its equilibrium length? incregyes 15. What happens to the potential energy of a spring if it is compressed from its equilibrium length? . increase p 16. What happens to the frequency of a vibration if you increase the force constant? ncrease 17. What happens to the frequency of a vibration if you increase the mass? decreayge 18. The vibrations of molecular bonds are not as simple as a symmetric parabolic graph. What is happening to the bond in a molecule as the energy levels out? (This is on the right side of the graph.) bond prea ks 19. What is the change in energy associated with an overtone? TYansitions ope [,u0 10 nigher 20. What must happen to the dipole for a specific vibration to show up in IR Spectroscopy? it must cha f’)q e 21. What are the three stretches that a water molecule has? pen SYManedlic mmetric NOT FOR DISTRIBUTION - FOR INSTRUCTORS USE ONLY

Bend N B9 pectrum in 23. Which takes more energy, a bend or a stretch? (Look at where they are on the s wavenumbers, and then look at your equation from question 9.) chetch 24. Draw the four molecular vibrations for CO, using arrows to show the direction of the stretch or bend. Label which one(s) will result in IR absorption. —_— 25. What is the range in wavenumbers of the fingerprint region? (Remember that we need a high and a low, not just “anything below...”) <400 NOT FOR DISTRIBUTION - FOR INSTRUCTORS USE ONLY

Your preview ends here