SPECTROSCOPY!

Question 1

How does Mass Spectrometry work?

Answer 1

1. Sample will loose electrons, become +ve ion, where m/z ratio is found!
2. Relative intensity shows prevalence of molecular ion
3. M+ peak = total molecular mass of sample (right-most), excluding isotope C-13 peak…

Question 2

What is Fragmentation?

Answer 2

• Where molecule breaks down upon ionising, where fragment ions are found as result….
• Must use common sense to judge what fragment ions will form from M+!
• Examples for fragment m/z = CH3+ >
  C2H5+ > 29, C3H7+ > 43, C4H9+ > 57

Question 3

How are covalent bonds affected by IR radiation?

Answer 3

1. Bonds can absorb IR, and vibrate/stretch/bend!
2. Magnitude depends on MASS of atoms, and STRENGTH of bonds!
3. Heavier = more, strong = faster….
4. Only absorbs frequency as bond’s natural frequency!, cm-1 used as frequencies are too large, still proportional!!

Question 4

Simple mechanisms behind IR spectroscopy!

Answer 4

1. Beam of IR between 4000 cm-1 and 200 cm-1 passed to sample
2. molecules absorb IR freqquencies, and beam existing after absorbtion is analysed!

Question 5

difference between carboxylic acid and alcohol spectra!

Answer 5

CA = MUCH BROADER PEAK, specific to range in Data Sheet + C=O MUST also be present
A = u-shaped peak, slimmer range….

Question 6

uses of IR spectroscopy, and how combined for MORE use??

Answer 6

1. Breathalysers for ethanol detection, GH gass detection, Poluutants detection
2. Combined with Elemental Analysis > empirical formula, Mass Spectrometery > Mr finding, all to identifyunkown compounds!!!!!