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Organic analysis
This topic introduces analytical evidence for functional groups and molecular structure.
7
Objectives
10
Flashcards
10
Questions
90 min
Study time
AqaA LevelChemistryOrganic chemistry
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Syllabus checklist
What you need to know
7 objective pages available
Test-tube reactions and mass spectrometry4 objectives
- Use test-tube reactions to identify alcohols, aldehydes, alkenes and carboxylic acids.
- Interpret mass spectra to identify molecular ion peaks.
- Use fragmentation evidence to support structural identification.
- Required practical: tests for alcohol, aldehyde, alkene and carboxylic acid.
Infrared spectroscopy3 objectives
- Use infrared absorption data to identify functional groups.
- Interpret the fingerprint region by comparison with reference spectra.
- Explain how infrared spectroscopy can monitor gases such as CO2, CH4 and H2O.
Key terms
Tollens' reagentBromine waterMolecular Ion PeakFragmentationMolecular ion peakDecolorizationInfrared SpectroscopyFunctional GroupFingerprint regionCarbonyl groupMolecular Vibration
Exam tips
- Be precise with observations: Always describe the color change or gas evolution clearly in your answers.
- Carefully analyze the mass spectrum: Pay close attention to the molecular ion peak and the fragmentation pattern to deduce the molecular formula.
Common mistakes
- Confusing alcohols with carboxylic acids: Use specific tests like the reaction with sodium bicarbonate to confirm the presence of a carboxylic acid.
- Confusing molecular ion peak with base peak: Remember that the molecular ion peak indicates the molecular weight, while the base peak represents the most abundant ion.
Practice preview
- Which of the following reagents can be used to distinguish between an alcohol and a carboxylic acid?
- Describe the test-tube reaction to identify an alkene and the expected observation.
- A sample of an unknown organic compound is suspected to be an aldehyde. Describe how you would confirm its identity using a test-tube reaction.
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