Mass spectra an IR
- Created by: danni :)
- Created on: 29-05-13 12:03
Other questions in this quiz
2. Gases that absorb IR are
- Inert gases
- Greenhouse gases
- Noble gases
3. Which of the following equations for the fragmentation of ethanol, CH3CH2OH, caused by collision with a high-energy electron, e−, would give a peak at m/e = 15 in its mass spectrum?
- CH3CH2OH + e− → CH3+ + •CH2OH + 2e−
- CH3CH2OH + e− → CH3• + +CH2OH + 2e−
- CH3CH2OH → CH3+ + +CH2OH + 2e−
- CH3CH2OH → CH3• + ·•CH2OH
4. Bromine exists as two isotopes, 79Br and 81Br in equal amounts and so has a molar mass of 80 g mol–1. How many major molecular ion peaks are there in the mass spectrum of CH2Br2?
- 4
- 3
- 1
- 2
5. It is suggested that IR spectroscopy can be used to show whether an alcohol has been oxidised to an aldehyde or to a carboxylic acid by comparing the IR spectra of the alcohol and its oxidation product. Which of the following statements is true?
- You cannot tell whether the alcohol has been oxidised to an aldehyde or a carboxylic acid because both give an IR absorption at around 1700 cm–1.
- The alcohol has been oxidised to an aldehyde if the broad O–H absorption at about 3300 cm–1 in the alcohol spectrum is replaced by a narrow C=O absorption at about 1700 cm–1 in the product spectrum
- You cannot tell to what the alcohol has been oxidised because these compounds do not absorb in the IR part of the spectrum.
- The alcohol has been oxidised to a carboxylic acid if it now has a broad C=O absorption at about 1700 cm–1 and has a narrow O–H absorption at 3300 cm–1 in the product spectrum.
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