Analytical techniques

Question 1

What is the plural terminology in spectroscopy?

Answer 1

Spectra

Question 2

What is the key ionization method used in mass spectrometry known as?

Answer 2

Electron ionization (EI)

Question 3

What does EI stand for in mass spectrometry?

Answer 3

Electron ionization

Question 4

What is a mass spectrum?

Answer 4

A vertical bar graph representing ions with a particular m/z ratio and their relative abundance.

Question 5

What are the intact molecules in a mass spectrum called?

Answer 5

Molecular ions

Question 6

What are the ions resulting from the breakdown of a molecule in mass spectrometry called?

Answer 6

Fragment ions

Question 7

What is the highest m/z ion typically present in a mass spectrum?

Answer 7

A form of the molecular ion

Question 8

What is the most intense ion in a mass spectrum known as?

Answer 8

Base peak

Question 9

What does the m/z value represent in mass spectrometry?

Answer 9

Mass to charge ratio

Question 10

True or False: Neutral molecules can be detected in mass spectrometry.

Answer 10

False

Question 11

What is the nitrogen rule in mass spectrometry?

Answer 11

Even m/z indicates even nitrogen atoms; odd m/z indicates odd nitrogen atoms.

Question 12

What isotopic ratio is used to identify chlorine in mass spectrometry?

Answer 12

75% 35Cl and 25% 37Cl

Question 13

What isotopic ratio is used to identify bromine in mass spectrometry?

Answer 13

50% 79Br and 50% 81Br

Question 14

What is a characteristic peak size for compounds containing one chlorine?

Answer 14

M+2 peak is one third the size of the molecular ion.

Question 15

What unusual characteristic peak do sulfur-containing compounds exhibit?

Answer 15

Larger than usual M+2 peak

Question 16

What is the range of the IR window in spectroscopy?

Answer 16

4000 cm⁻¹ to 500 cm⁻¹

Question 17

What do stretching vibrations in IR spectroscopy correspond to?

Answer 17

Increasing and decreasing bond lengths within a molecule.

Question 18

What do bending vibrations in IR spectroscopy correspond to?

Answer 18

Increasing and decreasing angles between bonds in a molecule.

Question 19

What are the N–O asymmetric and symmetric stretch wavenumbers in nitroalkanes?

Answer 19

• Asymmetric: 1550 cm⁻¹ * Symmetric: 1365 cm⁻¹

Question 20

What does the base peak represent in an EI mass spectrum?

Answer 20

The most stable fragment formed in the mass spectrometer.

Question 21

Fill in the blank: The tallest peak in an EI mass spectrum is called the _______.

Answer 21

base peak

Question 22

What is the disadvantage of a harsh fragmentation technique like Electron Ionization?

Answer 22

May not always observe the molecular ion due to fragmentation.

Question 23

What is an advantage of a harsh fragmentation technique like Electron Ionization?

Answer 23

Provides detailed fragmentation patterns for structure elucidation.

Question 24

What should you avoid interpreting in an IR spectrum?

Answer 24

The fingerprint region

Question 25

What is the significance of isotopic patterns in mass spectrometry?

Answer 25

Helps to confirm the presence of specific elements like halogens.

Question 26

What is the expected M+1 peak due to?

Answer 26

The presence of 13C isotope in the sample.

Question 27

What kind of information can IR spectroscopy provide?

Answer 27

Confirmation of functional groups in organic compounds.

Question 28

What is the absorption of IR radiation responsible for in molecular bonds?

Answer 28

Causes bonds to stretch and bend.

Question 29

What does the term 'molecular ion' refer to?

Answer 29

The intact ion of a molecule detected in mass spectrometry.

Question 30

What is the purpose of the detector in mass spectrometry?

Answer 30

To detect positively charged ions.