Analytical Techniques Flashcards
What is mass spectrometry used to measure?
Relative atomic masses of atoms and relative molecular mass of organic compounds
What are organic compounds?
(Generally) compounds that contain carbon
What is the charge of ions formed in a mass spectrometer meant to be?
1+
Give an example of application of the mass spectrometer?
Drug testing; especially in the case of urine samples in athletes (other suitable examples are expectable obviously :P )
What is C2H5OH+ known as? (assume numbers are in subscript)
A molecular ion
When molecular ions break up into ions of smaller molecular mass this is known as (…)?
Fragmentation
What does the main peak furthest to the right in a mass spectrum represent?
Molecular ion mass/relative atomic mass
What is the peak furthest to the right in the mass spectrum called?
Molecular ion peak
What is high resolution useful in measuring?
Parent ion’s molecular formula
What does a high resolution mass spectrometer take into account?
That the relative atomic masses of elements are not exactly a whole number (except in the case of carbon-12)
What would you use to distinguish between molecules that seem to have the same mass number when the elements relative masses used previously were whole numbers? (e.g. oxygen = 16)
High resolution mass spectrometry
How are substances separated before they are placed into a mass spectrometer?
Chromatography
What does IR stand for?
Infra-red
What is infra-red spectroscopy used for?
Identifying organic compounds (based on the wavelength absorbed by the bonds)
Do strong bonds vibrate at a lower or higher frequency?
Higher frequency
Is the frequency of a bond between two heavier atoms higher or lower?
Lower
What happens when we shine a beam of IR radiation at a sample?
Bonds absorb energy of the same frequency as the natural frequency of the bond. Radiation passes through with missing frequencies.
When a graph is plotted for the IR graph spectrometer what values go on the x and y axes respectively?
Wave number in cm-1 (the frequency) and transmission in %
When a graph is plotted for the mass spectrometer what value goes on the x and y axes respectively?
Relative abundance in % and mass charge ratio (m/z)
What do dips in an IR spectrum represent
Specific bonds
What are dips in an IR spectrum (confusingly) called?
Peaks
Wave numbers can help us identify (…)?
Functional groups
Can an IR spectrum identify impurities?
Yes
The area below 1500cm-1 in an IR spectrum contains vibrations of the whole called (…)?
Fingerprint region
Why does the mass to charge ration (a.k.a m/z) have no units?
Because it is a ratio
