spec b

Question 1

frequency unit

Answer 1

Hz or s^-1

increasing frequency = increasing E

Question 2

wavenumbers relationships

Answer 2

inversely proportional to wavelength

proportional to frequency

4000 cm^-1 to 400 cm^-1

Question 3

absorption based on bond strength and mass

Answer 3

bond strength: stronger bonds vibrate at higher freq

mass: lighter atoms vibrate at higher freq

Question 4

bond strength regions

Answer 4

4000-2500: bonds to H & lighter atoms

2500-2000: triple bonds

2000-1500: double bonds

<1500: single bonds

Question 5

wavenumbers relationship to s character

Answer 5

as s character increases, wavenumbers increases

(stronger bond)

Question 6

alpha,beta unsaturated bar only compound

Answer 6

• can we written as 3 res structures
  -two of which place a single bond b/w C & O atoms of carbonyl group
  -unconjugated carbonyl is only surrounded by single bonds

Question 7

single bond charcter vs freq

Answer 7

the more the res structures contribute to the hybrid, the more single bond charcter the carbonyl group has, and the lower freq of absorption

Question 8

amide carbonyl vs ester carbonyl

Answer 8

amide has more single bond character, so occurs at a lowest wavenumbers