• At AS level, you have used mass spectrometry to determine:
  • Relative atomic mass from isotopic abundance
  • Possible molecular formulae from molecular ion peaks
  • Organic structures from fragmentation patterns
• High resolution mass spectrometry?can be used to deduce / confirm molecular formulae
• High resolution mass spectrometers provide data accurate to four, or sometimes more, decimal places
• This means that a compounds molecular formula can sometimes be deduced by using atomic masses accurate to four decimal places

Table of selected accurate relative atomic masses

? ?Answer???

1. C4H10?= (4 x 12.0000) + (10 x 1.0078) = 58.0780
2. C2H6N2?= (2 x 12.0000) + (6 x 1.0078) + (2 x 14.0031) = 58.0530
3. C3H6O =(3 x 12.0000) + (6 x 1.0078) + (15.9949) = 58.0417

• Therefore, the correct formula of the compound is?C3H6O

转载自savemyexams