{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

3600_Ch22_probs - 21-3 The atomic mass in the periodic...

Info iconThis preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Background image of page 2
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: 21-3. The atomic mass in the periodic table is a weighted average ofthe masses of all the isotopes of mat element- We can estimate the reiatiire ahundanoe of the two major isotopes of Hi from the heights of their mass spectral peaks. The heights ofthe peeks that I measured from an earlier eersien of this illustration are 41.15 mm for 531511 and 17-1 mm for H'hii- The weighted average is atomie mass = {53141 massilli% abundance of 5W1} + {midi massitjfi: ahundanee of WM} 42.5 11". l = {51.935 “(Wit (59.933 Ei[m] = asst The atomic mass in the periodic table is 53.69- This main reason for disagreement is met we negleeted die esistenee ot'mhii [1.13%- natural abundance}, “Ni [3.59%], and MPH fflHUfiJ] 22-4. Reselving Fewer = fl = 2:133 = 1-5}: “1'1 We should he able to barely.r distinguish two peaks differing by ] Us at a mass of LE 1: 104' De- Therefore we should be able to distinguish two peaks at II] [III and ill} 11” Du. 22-5. It looks like the two peaks could be about half as far apart as they actually are and still be resolved. Their actual separation is 0.035 Da and they could probably be resolved if their separation were ~0.018 Da. The resolving power is approximately m/Am z 84/0018 z 5 000. 22-7. C5H7O+: 5 x 12.000 00 +7 x 1.007 825 +1 x 15.994 91 —e‘ mass ~1 x 0.000 55 83.049 14 C6H1+1: 6 x12.000 00 +11>< 1.007 825 —e‘ mass —1 x 0.000 55 83.085 52 C6H1+1 is a closer match than C5H7O+ to the observed mass of 83.086 5 Da. 11-1 ':-'. In a double—focusing mass speemter. ions ejrtsrd Elem the some: pose flireugh an eieetImtatie sector that seteets ions with a narrow hen-:1 of kinetic marries to continue into the magnetic sector. The electric sector acts as an energy filter and the magnetic sector acts as a momentum filter. 2 2 - 1 9 . The reflectron improves resolving power by ensuring that all ions of the same mass reach the detector grid at the same time. Ions from the ion source have some spread of kinetic energy. Faster ions penetrate deeper into the reflectron and therefore spend more time there before being turned around. The reflectron essentially allows slower ions to catch up to faster ions. ...
View Full Document

{[ snackBarMessage ]}