14 Analytical techniques (IR and MS) Flashcards
How can isomers be differentiated on a mass spectra?
m/z of fragments
What are two uses of IR spectroscopy?
detecting pollution / breath tests to detect alcohol
What information can elemental analysis give?
the empirical formula
Why is methane a greenhouse gas?
it re-emits radiation that warms the Earth
What is a molecular ion?
positively charged ion of the compound being tested
What happens to covalent bonds when they absorb IR radiation?
they bend or stretch
What is m/z?
mass to charge ratio
What order should you look at data from a range of analyses when trying to determine the identity of a compound?
elemental analysis, mass spectra, IR spectra
What two things determine the degree of bending and stretching of a bond after absorbing IR radiation?
the mass of the atoms and the strength of the bond
What is the name of the region that shows the characteristic of a functional group on an IR spectrum?
fingerprint region
Why do most compounds have a peak around 3000 cm−1?
this is due to absorption by C—H bonds
What group is identified by the peak produced between 3200 cm−1 and 3600 cm−1?
the O—H bond in an alcohol
Where would a peak in IR spectroscopy for a C—O bond be produced?
between 1000 and 1300 cm−1
Where would a peak in IR spectroscopy for a C=O bond in a aldehyde or a ketone be produced?
in the region 1630 cm−1 to 1820 cm−1
What functional group would you identify if an IR spectrum had a peak between 1630 cm−1 and 1820 cm−1 and a broad beak between 2500 cm−1 and 3330 cm−1?
a carboxylic acid
