What information does carbon-13 NMR spectroscopy provide about organic molecules?

It tells you where the carbon-13 atoms sit in the molecule.

Why do carbon atoms in different functional groups appear at different positions in a carbon-13 NMR spectrum?

Because different chemical shift values correspond to carbon atoms in different chemical environments.

Explain why propan-2-ol shows only two peaks in its carbon-13 NMR spectrum despite having three carbon atoms.

The two terminal methyl carbons are in identical chemical environments due to molecular symmetry, so they produce a single peak rather than two separate peaks.

What information does high resolution proton NMR spectroscopy provide about organic molecules?

It tells you where the hydrogen-1 atoms sit in the molecule.

Edexcel A-Level Chemistry 9CH0

Atomic Structure and the Periodic Table

Topic overview Protons, neutrons, electrons and isotopes Relative atomic mass and the mass spectrum Ionisation energy and the evidence for sub-shells Orbitals and electron configuration Periodicity across a period and down a group

Bonding and Structure

Topic overview Ionic bonding Covalent bonding, dative bonding and the shapes of molecules Electronegativity, polarity and intermolecular forces Structure and properties

Redox I

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Inorganic Chemistry and the Periodic Table

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Organic Chemistry I

Topic overview Formulae, homologous series and functional groups IUPAC nomenclature Types of organic reaction and structural isomerism Stereoisomerism and E/Z nomenclature Practical techniques in organic chemistry Alkanes, crude oil and combustion pollutants Radical substitution Alkenes, the double bond and hydrogenation Electrophilic addition, Markovnikov's rule and the test for an alkene Addition polymers and waste polymers Nucleophilic substitution of halogenoalkanes Rates of hydrolysis and the SN1 and SN2 mechanisms Classifying and oxidising alcohols Alcohols: practical techniques and the core practicals

Modern Analytical Techniques I

Topic overview Mass spectrometry Infrared spectroscopy and the characteristic absorptions Deducing functional groups from an infrared spectrum

Energetics I

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Kinetics II

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Organic Chemistry II

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Organic Chemistry III

Topic overview The structure of benzene and the evidence for it Electrophilic substitution of benzene Nitration, halogenation, Friedel-Crafts and phenol Amines: structure and basicity Reactions of amines and preparing them Amides and condensation polymers Amino acids, zwitterions and proteins Empirical and molecular formulae from analytical data Grignard reagents and multi-step synthesis Purification techniques and the aspirin preparation

Modern Analytical Techniques II

Topic overview Carbon-13 and proton NMR Splitting, integration and the reference standard Chromatography High-resolution mass spectrometry

Modern Analytical Techniques II

Carbon-13 and proton NMR

3 things to know
Papers 2 and 3

Overview

Recall questions on what NMR detects, on how many signals a molecule gives, and on the chemical shifts of the common carbon and proton environments.

What you need to know

Answer each one before you reveal it.

Your recallNot started

Key term

How can you determine the number of distinct carbon environments in a molecule from its carbon-13 NMR spectrum?

Key term

In carbon-13 NMR spectroscopy, what does the chemical shift value indicate?

Key term

In proton NMR spectroscopy, what does the chemical shift value indicate?

Questions from this subtopic

Each one with the model answer underneath.

1
What information does carbon-13 NMR spectroscopy provide about organic molecules?
Model answer
It tells you where the carbon-13 atoms sit in the molecule.
2
In carbon-13 NMR spectroscopy, what does the chemical shift value indicate?
Model answer
The chemical shift value indicates the electronic environment of a carbon atom.
3
Why do carbon atoms in different functional groups appear at different positions in a carbon-13 NMR spectrum?
Model answer
Because different chemical shift values correspond to carbon atoms in different chemical environments.
4
How can you determine the number of distinct carbon environments in a molecule from its carbon-13 NMR spectrum?
Model answer
The number of peaks in the spectrum equals the number of distinct carbon environments in the molecule.
5
Explain why propan-2-ol shows only two peaks in its carbon-13 NMR spectrum despite having three carbon atoms.
Model answer
The two terminal methyl carbons are in identical chemical environments due to molecular symmetry, so they produce a single peak rather than two separate peaks.
6
What information does high resolution proton NMR spectroscopy provide about organic molecules?
Model answer
It tells you where the hydrogen-1 atoms sit in the molecule.

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