Spectroscopy

Question 1

Name the use of mass spectra outside the lab

Answer 1

Breathalizers

Monitoring of air pollution

MOT emissions testing

Question 2

How does IR interact with a greenhouse gas molecule?

Answer 2

Greenhouse gas absorbs it and its bonds vibrate

Question 3

What factors affect a gases global warming potential?

Answer 3

Residence time
Amount of IR absorbed
Concentration of gas in atmosphere

Question 4

What produces the molecular ion?

Answer 4

The molecule once it loses an electron

Question 5

What is the M+ peaks m/z value equal to?

Answer 5

The RMM of the molecule

Question 6

What does m/z stand for?

Answer 6

Mass/charge

Question 7

How does a mass spectrometer work?

Answer 7

Bombards molecule with electrons

Produces 1+ ions

M/z detected by detector

Heavier ions have a larger m/z value

Question 8

Why is there a M+1 peak

Answer 8

Due to presence of C13 isotope (1.1%)

Question 9

What is the name of the process when a molecular ion breaks into smaller ions

Answer 9

Fragmentation

Question 10

What does fragmentation produce

Answer 10

Fragment ion peaks

Question 11

When a molecular ion fragments what is produced?

Answer 11

Ion and a radical

Question 12

Why can fragment ions be used to identify a molecular structure?

Answer 12

Different isomers will fragment in different ways

Question 13

How does IR spectrometry work?

Answer 13

Different bonds absorb different wavelengths of IR

Question 14

What increases the vibration of bonds

Answer 14

Increase in temp

Question 15

Why are atoms in constant motion despite being held in place by bonds

Answer 15

The bonds naturally vibrate

Question 16

What are the two type of bond vibration

Answer 16

Bending and stretching

Question 17

Describe the stretching of a bond

Answer 17

Distance between two atoms increases and decreases along line between atoms

Question 18

Describe the being of a bond

Answer 18

Bond angle increases and decreases

Question 19

What factors affect the vibration of a bond?

Answer 19

Mass of atoms

Bond strength

Question 20

How does the mass of atoms affect the vibration of a bond?

Answer 20

Heavier mass= slower vibration

Question 21

How does bond strength affect the vibration of a bond?

Answer 21

Stronger= faster vibration

Question 22

What are the main greenhouse gases

Answer 22

Water vapour, methane and carbon dioxide

Question 23

How do greenhouse gases cause global warming

Answer 23

Absorb longer wavelength radiation reflected off of earth’s surface and re-radiates it as thermal energy

Question 24

What do the peaks on a IR spectra indicate

Answer 24

Bonds present in a molecule

Question 25

What is the finger print region

Answer 25

The region on a IR spectra that is unique to every molecule

Question 26

How can fingerprint regions be used to identify a molecule

Answer 26

Compare to database

Question 27

What are the applications of IR spectrometry

Answer 27

Monitoring levels of greenhouse gases

Breathalizers