Infrared spectroscopy - WM

Question 1

Why is infrared spectroscopy done

Answer 1

to identify the different types of bonds present in the molecule and then what functional group

Question 2

How can you work out the bond type from the infrared spectroscopy

Answer 2

as each different compound will give its own unique infrared spectroscopy , when IR is shone at a molecule when it absorbs a certain frequency a peak is given and then these are used to determine the bonds

Question 3

What is frequency measured in on a infrared spectroscopy and units

Answer 3

wavenumber cm^-1

Question 4

How to convert wavenumber into frequency (e.g. 100 cm^-1)

Answer 4

1/100 = cm divide by 100 = 1/10000 =m
then use c=λv

Question 5

Why are peaks on a infrared spectroscopy different to normal

Answer 5

they go down the paper instead of up (troughs not peaks)

Question 6

What does a C=O peak look like on a infrared spectroscopy

Answer 6

strong peak around 1700cm^-1

Question 7

What does a O-H peak look like on a infrared spectroscopy (and what to be careful of)

Answer 7

a broad peak to the left but C-H peaks are also to the left but C-H bonds are much more sharp.

Question 8

What is the difference in carboxylic acid and alcohol -OH groups on a infrared spectroscopy

Answer 8

alcohol - broad peak slightly more left and OH is separated from C-H peak (https://docbrown.info/page06/spectra/ethanol-ir.gif)
carbox. acid - broad peak but C-H peak is combined with OH
(https://www.docbrown.info/page06/spectra/ethanoic-acid-ir.gif)

Question 9

What are the peaks lower than 1500cm^-1 called on a infrared spectroscopy

Answer 9

the fingerprint region

Question 10

What is the fingerprint region for on a infrared spectroscopy

Answer 10

check the identification of a molecule as each molecule gives a unique pattern