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Alevel Chemistry OCR A > Module 4: Analysis > Flashcards

Module 4: Analysis Flashcards

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1
Q

Mass spectrometry
What happens in the mass spectrometry

A

High energy electron bombards a molecules in a mass spectrometer which results in the molecule losing an electron

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2
Q

Mass spectrometry
What is the resulting species when a molecule is bombarded by the higher energy electron

A

Molecular ion

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3
Q

Mass spectrometry
Equation for formation of molecular ion

A

Molecule —-> Molecule+. + e-

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4
Q

Mass spectrometry
Notation for molecular ion

A

M+

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5
Q

Mass spectrometry
What is the definition of a molecular ion

A

Positive ion formed when molecule loses an electron

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6
Q

Mass spectrometry
What is on the axis of a spectra

A

X- m/z -mass to charge ratio
Y- %abundance

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7
Q

Mass spectrometry
Where is the M+ ion on a spectra

A

Last peak on the right

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8
Q

Mass spectrometry
What is fragmentation

A

Process in mass spec that causes positive ion (M+) to split into pieces of a positive ion (which produces a peak) and a radical

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9
Q

Mass spectrometry
What is the M+1 peak

A

Smallll peak just after M+

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10
Q

Mass spectrometry
Why is the M+1 peak there

A

Due to C-13 present

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11
Q

Mass spectrometry
How is it used for isotopes

A

Positions of peaks show different isotopes prescence and is used to find relative atomic mass with abundance

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12
Q

Mass spectrometry
How can organic molecules be identified from eac other

A

Each have different peaks from fragments

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13
Q

Mass spectrometry
How does fragmentation occur and how does it show on spectra

A

One bond broken in the M+ to form a positive ion and radical
Peak at the positive ion formed with its m/z value (mr)

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14
Q

Mass spectrometry
Where is the Mr of the whole product found

A

At the M+ ion

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15
Q

Mass spectrometry
For analysis questions what is the typical way to find the molecular formula

A

Find the empirical formula and find mr
Find mr of whole product at the M+ peak
mr of whole product / Mr of empirical
Scale up the ration of the empirical formula

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16
Q

Mass spectrometry
What are fragmentation patterns of functional groups

A

Specific positions of peaks and differences between major peaks which makes it possible to identify the type of compound

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17
Q

Mass spectrometry
What is the peak due to at m/z 15

A

CH3+

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18
Q

Mass spectrometry
What is the peak due to at m/z 29

A

C2H5+

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19
Q

Mass spectrometry
What os the peak due to at m/z 43

A

C3H7+

20
Q

Mass spectrometry
For alkanes what affects the abundance of a peak

A

The stability of the carbo cation

21
Q

Mass spectrometry
For alkanes as the stability of the carbocation increases what happens to the peak

A

Larger abundance

22
Q

Mass spectrometry
For haloalkanes why is there often multiple peaks in the molecular ion region

A

Due to the different isotopes of the halogen

23
Q

Mass spectrometry
For ketones and aldehydes what is the characteristic fragmentation

A

Cleavage of bonds next to carbonyl (C=O)

24
Q

Mass spectrometry
Where do carbonyl compound fragments

A

Ether side of the carbonyl group

25
Q

Infra red spectroscopy
What is IR based on

A

Atoms molecules and ions ability to absorb electromagnetic radiation of specific frequencies and this can be used to identify them

26
Q

Infra red spectroscopy
What is the energy from IR used to do the molecules

A

Vibrate bonds

27
Q

Infra red spectroscopy
What is specific about each bind which allows them to be identifie

A

Vibrate at different frequency

28
Q

Infra red spectroscopy
What are the three types of bond vibration

A

Symmetric stretch
Asymmetric stretch
Bending

29
Q

Infra red spectroscopy
What is the graph called in IR

A

IR spectra

30
Q

Infra red spectroscopy
What is the range for IR to be absorbed

A

400-4000

31
Q

Infra red spectroscopy
What is below 1500 on a spectra

A

Fingerprinting -not used

32
Q

Infra red spectroscopy
What is above 1500 used for

A

Identifying functional group

33
Q

Infra red spectroscopy
Where is the info for where the identification of each functional group is

A

On data sheet

34
Q

Infra red spectroscopy
What does a C=C bond look like

A

Short spike around 1600 half way down spectra

35
Q

Infra red spectroscopy
What does a C=O bond look like

A

Long spike around 1700

36
Q

Infra red spectroscopy
What does )-H in an alcohol look like

A

Smooth peak wider around and above 3000

37
Q

Infra red spectroscopy
What does an O-H in a carbpxylic acid look like

A

Wide jaggeder peak at and above 3000

38
Q

Infra red spectroscopy
What are the two uses

A

Greenhouse gases identifying
Breathalysers

39
Q

Infra red spectroscopy
What are the green house gases 3

A

Carbon dioxide
Water vapour
Methane

40
Q

Infra red spectroscopy
How can carbon dioxide be identifies

A

C=O bond

41
Q

Infra red spectroscopy
How can water vapour be identified

A

O-H bonds

42
Q

Infra red spectroscopy
What does the greenhouse effect of a given gas depend onn

A

Atmospheric pollution
Ability to absorb infrared radiation

43
Q

Infra red spectroscopy
Why do bond have different strengths resulting in diffeeent frequencies vibrated at

A

Masses of different atoms at either end of bond

44
Q

Infra red spectroscopy
What is the type of vibration in water

A

Bending and stretching

45
Q

Infra red spectroscopy
What does infra red have to do with global warming

A

It’s the absorption of IR that contributes to global warming

46
Q

Infra red spectroscopy
How does iR work in breathalysers to measure alcohol levels

A

Ray of IR passed throught the breath that’s exhaled into breathalyser chamber
Characteristic bonds of ethanol are detected and measured higher absorbance-more ethanol

Alevel Chemistry OCR A (14 decks)

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