Analytical techniques

Question 1

Infrared (IR) spectroscopy

Answer 1

a technique used to identify compounds based on changes in vibrations of atoms when they absorb IR of certain frequencies

Question 2

spectrophotometer

Answer 2

irradiates the sample with electromagnetic waves in the infrared region and then detects the intensity of the wavelength of IR radiation which goes through the sample

Question 3

IR radiation and organic compounds

Answer 3

-All organic molecules absorb IR radiation and depending on which energies of radiation are absorbed, bonds between atoms will vibrate by stretching, bending and twisting
-The resonance frequency is the specific frequency at which the molecules will vibrate to stimulate larger vibrations
-Depending on the rest of the molecule, each vibration will absorb specific wavelengths of IR radiation which are also shown as the reciprocal of the wavelength

Question 4

Characteristics of particular absorbances

Answer 4

Particular absorbance have characteristic widths (broad or sharp) and intensities (strong or weak)

Question 5

Why should other analytical techniques such as mass spectroscopy should be used alongside IR spectroscopy to identify an unknown compound

Answer 5

Due to some absorption bands overlapping each other

Question 6

Mass spectroscopy

Answer 6

an analytical technique used to identify unknown compounds

Question 7

How mass spectroscopy works

Answer 7

-The molecules in the small sample are bombarded with high-energy electrons which can cause the molecule to lose an electron
-This results in the formation of a positively charged molecular ion with one unpaired electron
-The molecular ion can further fragment to form new ions, molecules, and radicals
-These fragmentation ions are accelerated by an electric field
-Based on their mass (m) to charge (e) ratio, the fragments of ions are then separated by deflecting them into the detector
-The smaller and more positively charged fragment ions will be detected first as they will get deflected the most and are more attracted to the negative pole of the magnet
-Each fragment corresponds to a specific peak with a particular m/e value in the mass spectrum
-The base peak is the peak corresponding to the most abundant ion