Infrared Spectroscopy

Question 1

What is infrared light absorbed by?

Answer 1

Molecules, causing the bonds to vibrate

Question 2

What are the consequences of infrared light being absorbed by molecules?

Answer 2

-global warming
-earth emits infrared light which is absorbed by some molecules in our atmosphere(Co2, Ch4, H2O)
-this is then re emitted back to us, heating the earth

Question 3

How is this helpful for chemistry?

Answer 3

-different bonds absorb different frequencies of infrared radiation
-we can measure the frequencies that get absorbed and see what bonds are in a molecule

Question 4

What is strange about the X axis on the infrared spectroscopy?

Answer 4

-the X axis scale is backwards
-The X axis scale changes past 2000cm^-1

Question 5

What does a large well defined peak at about 1700 show?

Answer 5

-A c=o double bond
-this suggests ketone, aldehyde or carboxylic acid

Question 6

What does a Wide U shaped peak at about 3500cm^-1 suggest?

Answer 6

An O-H bond in an alcohol

Question 7

What does a wide, untidy peak at about 3000cm^-1 indicate?

Answer 7

An O-H bond in a carboxylic acid

Question 8

What is the fingerprint region and what does it do?

Answer 8

-it is wavenumbers below about 1500cm^-1
-region is unique to each molecule and can be compared to published spectra to determine exactly which molecule is being studied