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CHEMISTRY A LEVEL > 3.15 NMR spectroscopy > Flashcards

3.15 NMR spectroscopy Flashcards

1
Q

What are the 2 main types of NMR?

A
  • C13 NMR

- H (proton) NMR

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2
Q

In C13 NMR spectrum, how many signals (peaks) are there for each set of equivalent C atoms?

A

In C13 NMR spectrum, there is one signal (peak) for each set of equivalent C atoms

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3
Q

How many signals (peaks) does propanal have in the C13 NMR spectrum?

A

3 peaks

see page 1 in the chemrevise revision guide

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4
Q

How many signals (peaks) does ethyl ethanoate have in the C13 NMR spectrum?

A

4 peaks

see page 1 in the chemrevise revision guide

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5
Q

How many signals (peaks) does 2-methylbutane have in the C13 NMR spectrum?

A

4 peaks

see page 1 in the chemrevise revision guide

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6
Q

How many signals (peaks) does ethnoic anhydride have in the C13 NMR spectrum?

A

2 peaks

see page 1 in the chemrevise revision guide

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7
Q

How many signals (peaks) does 2-chloro-2-methylpropane have in the C13 NMR spectrum?

A

2 peaks

see page 1 in the chemrevise revision guide

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8
Q

How many signals (peaks) does 4-nitro-1-methylbenzene have in the C13 NMR spectrum?

A

5 peaks

see page 1 in the chemrevise revision guide

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9
Q

How many signals (peaks) does 1,2-dinitrobenzene have in the C13 NMR spectrum?

A

3 peaks

see page 1 in the chemrevise revision guide

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10
Q

How many signals (peaks) does 1,3-dinitrobenzene have in the C13 NMR spectrum?

A

4 peaks

see page 1 in the chemrevise revision guide

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11
Q

How many signals (peaks) does 1,4-dinitrobenzene have in the C13 NMR spectrum?

A

2 peaks

see page 1 in the chemrevise revision guide

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12
Q

How many signals does ethanol have in the H (proton) NMR spectrum?

A

3 signals
Ethanol has 3 groups of different hydrogen atoms.

(see page 1 in the chemrevise revision guide)

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13
Q

What is the intensity (integration value) of each signal proportional to in the H (proton) NMR spectrum?

A

The intensity (integration value) of each signal is proportional to the number of equivalent H atoms it represents.

(see page 1 in the chemrevise revision guide)

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14
Q

What is the ratio of the equivalent H’s in 2-methylbutane in H (proton) NMR?

A

4 sets of equivalent H’s
6:1:2:3

(see page 1 in the chemrevise revision guide)

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15
Q

What is the ratio of the equivalent H’s in propanone in H (proton) NMR?

A

1 signal

see page 1 in the chemrevise revision guide

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16
Q

What is the ratio of the equivalent H’s in methyl propanoate in H (proton) NMR?

A

3 set of equivalent H’s
3:2:3

(see page 1 in the chemrevise revision guide)

17
Q

What is the ratio of the equivalent H’s in 2-bromobutane in H (proton) NMR?

A

4 sets of equivalent H;s
3:1:2:3

(see page 1 in the chemrevise revision guide)

18
Q

What is the ratio of the equivalent H’s in 1,1-dimethylethyl propanoate in H (proton) NMR?

A

3 sets of equivalent H’s
3:2:9

(see page 1 in the chemrevise revision guide)

19
Q

What is the ratio of the equivalent H’s in prop-1-ene in H (proton) NMR?

A

3 sets of equivalent H’s
3:1:2

(see page 1 in the chemrevise revision guide)

20
Q

Why are samples dissolved in solvents without any 1H atoms for the H NMR? Give two examples of these solvents.

A

This means that in the H NMR the solvent will not give any peaks.
CCL4
CDCl3

21
Q

Why is a small amount of TMS (tetramethylsilane) added to the sample in both C13 and H NMR spectroscopy?

A

To calibrate the sprectrum.

TMS is used because:

  • its signal is away from all the others
  • it only gives one signal
  • it is non-toxic
  • it is inert
  • it has a low boiling point and so can be removed from sample easily
22
Q

What does the squiggle (that kinda looks like partial charge symbol but I can write it on here) mean? (see page 2 in the chemrevise revision guide for the symbol)

A

It is a measure in parts per million (ppm) is a relative scale of how far the frequency of the proton signal has shifted away from that for TMS.

23
Q

Draw the displayed formula for tetramethylsilane.

A

(see page 2 in the chemrevise revision guide)

24
Q

Read bottom half of page 2 in the chemrevise revision guide.

A

Understand?

25
Q

Read bottom half of page 3 in the chemrevise revision guide.

A

Understand?

26
Q

For a singlet signal:

  • What does it look like on the spectra?
  • How many split number of peaks?
  • The number of neighbouring inequivalent H atoms?
  • The relative size?
A

(see page 4 in the chemrevise revision guide)

27
Q

For a doublet signal:

  • What does it look like on the spectra?
  • How many split number of peaks?
  • The number of neighbouring inequivalent H atoms?
  • The relative size?
A

(see page 4 in the chemrevise revision guide)

28
Q

For a triplet signal:

  • What does it look like on the spectra?
  • How many split number of peaks?
  • The number of neighbouring inequivalent H atoms?
  • The relative size?
A

(see page 4 in the chemrevise revision guide)

29
Q

For a quartet signal:

  • What does it look like on the spectra?
  • How many split number of peaks?
  • The number of neighbouring inequivalent H atoms?
  • The relative size?
A

(see page 4 in the chemrevise revision guide)

30
Q

Decide the signal peaks in ethyl ethanoate

A

(see page 4 in the chemrevise revision guide)

31
Q

Decide the signal peaks in methyl propanoate

A

(see page 4 in the chemrevise revision guide)

32
Q

Decide the signal peaks in ethanol

A

(see page 4 in the chemrevise revision guide)

33
Q

Read all of page 5 in the chemrevise revision guide

A

Understand? Make some flashcards on it.

34
Q

If you see a triplet + triplet in proton NMR, what does this tell you?

A

(see my own drawing on page 3 in the chemrevise revision guide)

35
Q

If you see a triplet + quartet in proton NMR, what does this tell you?

A

(see my own drawing on page 3 in the chemrevise revision guide)

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