1.2: Mass SPec
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Online Mass Spec Simulator 1
Online Mass Spec Simulator 2 Mass Spec = Mass Spectronomy. Not spectroscopy. This is very important to some people. Basic Principle: Step 1: Make your molecule (positively) charged. Step 2: Shoot your sample through something that separates it by mass Step 3: See how heavy the stuff coming through is. There are approximately 29,325* different methods of doing step one, and 500* ways of doing step two. * Ok, I did make those numbers up, but that's not the point. |
Heavier atoms/molecules have more momentum, and are therefore deflected (curved) less than the lighter ones.
Therefore, you are measuring the mass of each individual atom/molecule as it goes through the instrument. |
So what do you get out of this?
Chloroethane is C2H5Cl.
Remember that you are seeing individual atoms/molecules, and NOT the averages.
The peak labeled 'M' is from all the elements with their lightest isotopes--12C, 1H, and 35Cl
'M+2' comes from some molecules that have a 37Cl. It's smaller because only about 25% of chlorine atoms have a mass of 37.
A very good spectrum might show a tiny peak at a mass of 65--from having a 13C (about 1% of carbons), and maybe even a peak at 67 that comes from having both a 37Cl and a 13C in the same molecule.
Hydrogen has no isotopes with detectable amounts in a normal spectrometer.
All the peaks smaller than 64 come from some percentage of the molecules breaking apart--you are doing truly awful things to them. In research, the pattern and masses of these breakdown products are very important, but they are beyond the scope of AP chem.
Remember that you are seeing individual atoms/molecules, and NOT the averages.
The peak labeled 'M' is from all the elements with their lightest isotopes--12C, 1H, and 35Cl
'M+2' comes from some molecules that have a 37Cl. It's smaller because only about 25% of chlorine atoms have a mass of 37.
A very good spectrum might show a tiny peak at a mass of 65--from having a 13C (about 1% of carbons), and maybe even a peak at 67 that comes from having both a 37Cl and a 13C in the same molecule.
Hydrogen has no isotopes with detectable amounts in a normal spectrometer.
All the peaks smaller than 64 come from some percentage of the molecules breaking apart--you are doing truly awful things to them. In research, the pattern and masses of these breakdown products are very important, but they are beyond the scope of AP chem.
