Module 4: Analytical Techniques (Chapter 17)

Question 1

Give two examples of when infrared spectroscopy can be used in real life?

Answer 1

Breathalysers and in detecting levels of air pollution

Question 2

How do breathalysers use infrared spectroscopy?

Answer 2

Detect the presence of an -OH group of the ethanol (alcohol) on the breath
This is between wavenumbers 3200-3600 cm-3

Question 3

Why are HFCs more beneficial than the use of CFCs?

Answer 3

HFC’s do not break down the ozone, as there are no chlorine molecules which can be broken from the C-Cl bond in a CFC by UV radiation.

Question 4

How are HFCs still disadvantageous in terms of global warming?

Answer 4

Still a form of greenhouse gas and the H bonds are absorbed by the IR radiation, which prevents the IR being reflected back into the atmosphere, keeping the Earth warm and enhancing global warming.

Question 5

How would two carbonyl compounds differ on a mass spectrum?

Answer 5

Have different molecular ion peaks at different mass to charge ratios

Question 6

What does the M+1 peak show?

Answer 6

Small levels of the isotope carbon-13 is present in the sample