AQA A-Level Chemistry 7405
Atomic Structure
Amount of Substance
Bonding
Energetics and Thermodynamics
Kinetics
Chemical Equilibria
Redox and Electrochemistry
Acids and Bases
Periodicity and Group Chemistry
Period 3 Elements and Their Oxides
Transition Metals
Introduction to Organic Chemistry
Hydrocarbons
Halogenoalkanes, Alcohols and Organic Analysis
Carbonyls, Carboxylic Acids and Derivatives
Aromatic Chemistry and Amines
Polymers, Amino Acids, Proteins and DNA
Organic Synthesis, NMR and Chromatography
Organic Synthesis, NMR and Chromatography
Carbon-13 NMR Interpretation
- 3 things to know
- Papers 2 and 3
Overview
Counting carbon environments, and using them to tell isomers apart.
What you need to know
Answer each one before you reveal it.
What information does a carbon-13 NMR spectrum provide about a molecule?
What does each peak in a carbon-13 NMR spectrum represent?
Questions from this subtopic
Each one with the model answer underneath.
- 1
What information does a carbon-13 NMR spectrum provide about a molecule?
Model answer
The number of different carbon environments in the molecule
- 2
What does each peak in a carbon-13 NMR spectrum represent?
Model answer
A different carbon environment (carbons in different chemical surroundings)
- 3
How does the number of peaks in a carbon-13 NMR spectrum relate to the structure of a molecule?
Model answer
The number of peaks equals the number of different carbon environments, not necessarily the number of carbon atoms
- 4
What does it mean when two carbon atoms in a molecule give rise to a single peak in carbon-13 NMR?
Model answer
The two carbon atoms are in equivalent chemical environments
- 5
How can carbon-13 NMR be used to distinguish between structural isomers?
Model answer
Different structural isomers have different numbers and/or positions of carbon environments, giving different numbers of peaks
- 6
If a molecule has a plane of symmetry, how does this affect the number of peaks in its carbon-13 NMR spectrum?
Model answer
Symmetry makes some carbon atoms equivalent, reducing the number of peaks below the total number of carbon atoms
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