National Textile University – Faisalabad Assignment 01 – Fall 2010

( Due date: 14-11-2011)

Total Marks: 10

Q.1. How can you identify the primary N-H and secondary N-H in IR spectrum?

Q.2. Explain the difference between frequency and wavenumber.

Q.3. Give the mathematical relationship of wavelength with (i) frequency (ii) wavenumber (iii) energy

Q.4. Determine the wavenumber of each of the two waves having wavelength of 104 nm and 4 µm respectively.

Q.5. Calculate the energy in kj/mol of violet and red lights which have wavelengths of 400 and 800 nm respectively.

Q.6. How does an electronically excited molecule return to the ground state.

Q.7. What kind of information about a compound is provided by each of following spectroscopic techniques? (i) UV (ii) IR (iii) NMR (iv) MS

Q.8. Explain the instrumental details of FT-IR spectrophotometer.

Q.9. Using Hooke’s law calculate the wavenumber and wavelength of IR radiation absorbed due to stretching vibration of C=O group. The mass value for C and O are 19.92 x 10-24 g and 26.56 x 10-24 g respectively and the force constant for double bond is 10 x 105 g s-2.

Q.10. Explain why the stretching frequency of the O-D bond is 2600 cm-1 whereas that of O-H bond is 3600 cm-1 although both have almost same force constant?

Q.11. The stretching frequency of the C-H bond decreases as following ≡C-H (3300 cm-1) > =C-H (3100 cm-1) > -C-H (2900 cm-1), How will you explain it?

Q.12. Why conjugation of C=O with C=C lowers its stretching frequency?

Q.13. Define chemical shift and explain how it is measyured?

Q.14. Interpret the following IR and NMR spectra.

Problem-1 C5H10O

Problem-2, C7H14O

Problem3, C4H10O

Problem4, C6H14O

Problem5, C4H8O2

Problem6, C5H10O2

Problem7: C5H10O

Problem8: C8H8O

Problem9: C9H10O2

Problem 10: C3H6O2

Problem11 : C11H14O2

Problem12 : C8H8O2

Problem 13: C7H9N

Problem14 : C5H13N

Problem15 : C8H14O