Modern Analytical Techniques II

What Modern Analytical Techniques II covers

Covers carbon-13 and proton NMR and what each feature of a spectrum reveals, and the chromatographic methods that separate a mixture before analysis.

The 4 subtopics

Each one has its own page.

• Carbon-13 and proton NMRRecall questions on what NMR detects, on how many signals a molecule gives, and on the chemical shifts of the common carbon and proton environments.Open →
• Splitting, integration and the reference standardRecall questions on the n plus one rule, on reading an integration trace, on the deuterium exchange for OH and NH, and on why TMS is used as the standard.Open →
• ChromatographyMobile and stationary phases and how they separate a mixture, calculating Rf values, HPLC and gas chromatography as column methods, retention time, and coupling GC or HPLC to mass spectrometry for uses such as forensic work and drug testing.Open →
• High-resolution mass spectrometryAccurate relative molecular masses to four decimal places, why carbon-12 is exactly 12.0000, calculating accurate masses from isotopic masses, telling apart formulae with the same whole-number Mr such as CO, N2 and C2H4, and why an accurate mass alone cannot identify a structure.Open →

What you need to know

Answer each one before you reveal it.

Take Modern Analytical Techniques II further

The same content, four other ways.

Commonly confused

Pairs that lose marks when they are blurred together.

• Chemical shift vs Integration trace

  Chemical shift: resonance position relative to a reference signal. Integration trace: relative area showing proton ratios.

• Carbon-13 NMR vs Proton NMR

  Carbon-13 NMR: spectroscopy showing distinct carbon environments. Proton NMR: spectroscopy showing hydrogen environments, ratios and splitting.

• Stationary phase vs Mobile phase

  Stationary phase: phase remaining fixed during separation. Mobile phase: phase moving through or over the fixed phase.

Questions from this topic

Each one with the model answer underneath.

1. 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. 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. 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. 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. 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. 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.

What is inside Levo

Six ways to work the same material.

Modern Analytical Techniques II revision questions

What does Modern Analytical Techniques II cover in Edexcel A-Level Chemistry?

4 subtopics: carbon-13 and proton nmr, splitting, integration and the reference standard, chromatography and high-resolution mass spectrometry. Each one has its own page with questions and model answers.

How is Modern Analytical Techniques II organised?

By the Edexcel 9CH0 specification, subtopic by subtopic, so it matches the order you are taught it in.