Mass Spectrometry

15 Points Per Correct Answer - No time limit  

1. Who was credited for the invention of the mass spectrometer? Neils Bohr Ernest Rutherford J.J. Thompson James Chadwick

2. In a mass spectrometer, molecules are bombarded with high-speed electrons and are ionized before broken into smaller fragments, namely cations and radicals. Which species will be detected by the mass spectrometer? Radicals Cations Both of these None of these

3. Ions formed in a mass spectrometer will be separated by magnetic deflection. The radius of curvature of the ion's path depends on the ratio of m/z. (m is the mass and z is the charge of the ion). Which of the following ions will bend the most? Ion C with m = 10 and z = +2 Ion A with m = 10 and z = +1 Ion B with m = 20 and z = +1 Ion D with m = 20 and z = +2

4. The peaks shown by a mass spectrum are given in terms of relative abundance, where the strongest peak (also known as the base peak) is assigned a value of 100%. On the other hand, the parent peak (also known as the molecular ion peak) is the peak shown by the molecular ion, M+ after losing only 1 electron (without undergoing any fragmentation). Will this parent peak always be the base peak? Yes No

5. The peak with the greatest m/z value for alcohols is given by m/z M-18, where M represents the molecular weight of the alcohols. The number 18 in “M-18” means that the radical cation loses a (an) ___ molecule. Carbon dioxide, CO2 Water, H2O Ethene, C2H4 Carbon monoxide, CO

6. The most common fragmentation pattern for alkanes is the one that occurs at the molecules’ branches. True False

7. The presence of which element in any compound is characterized by an odd number of m/z for its parent peak? Sulfur, S Phosphorus, P Oxygen, O Nitrogen, N

8. You notice that a mass spectrum shows the equal intensity (peak) for both m/z at M+ (molecular ion) and M+2 (the molecular weight of the compound plus 2). Which element is present in the compound? Boron, B Chlorine, Cl Bromine, Br Nitrogen, N

9. The mass spectrum of 2, 2-dimethylpropane, (CH3)4C shows a base peak (the peak with the highest intensity) at m/z 57. This m/z 57 corresponds to the (CH3)3C+ species. What kind of carbocation is it? Primary Tertiary Secondary Quaternary

10. An unknown chemical compound is given to you and you run a test by using a normal mass spectrometer. From the spectrum, you know that the molecular weight of the compound is 28. This 28 indicates that your compound might be CO, C2H4 or N2, since the molecular formulae for these three compounds are 28 as well. You decide to put the compound in an HR-MS this time to determine the correct molecular formula of this compound. What does HR-MS stand for? Half-Resonance Mass Spectrometer High-Resonance Mass Spectrometer High-Resolution Mass Spectrometer Half-Resolution Mass Spectrometer