Module 4: Analytical techniques

Question 1

Infrared spectroscopy.

Answer 1

A process using infrared radiation to identify the functional groups in an organic compound.

Question 2

Describe the infrared spectroscopy process

Answer 2

• sample placed in the IR spectrometer
• a beam of IR radiation (200-4000 cm-1) is passed through the sample
• molecule absorbs some of the frequencies and the emerging beam is studied to see which frequencies have been absorbed
• a computer plots the wave of transmittance on a graph

Question 3

Fingerprint region.

Answer 3

In an IR spectrum, the region of 1400 to 400 cm-1 where more complex vibration patterns, caused by the motion of the molecule as a whole, can be seen; it is characteristic of each individual molecule.

Question 4

what are some of the applications of IR spectroscopy?

Answer 4

• IR breathalysers to test for alcohol consumption

Question 5

what is the typical sequence for identification

Answer 5

• elemental analysis
• mass spectrometry
• infrared spectroscopy

Question 6

what does elemental analysis involve

Answer 6

analysis of the percentage composition of the compound to derive empirical formulae