Purification and Characterisation of Organic Compounds Cheatsheet

Cheat Codes & Shortcuts

• Definition: Purification isolates a compound; characterisation determines its structure and properties.
• Crystallisation: Dissolve in hot solvent, cool to form crystals.
• Distillation: Separate based on boiling point differences.
• Chromatography: Separates based on differential adsorption or partitioning.
• Melting Point: Indicates purity; sharp for pure compounds.
• Boiling Point: Used for liquid identification and purity check.
• IR Spectroscopy: Identifies functional groups via absorption bands.
• NMR Spectroscopy: Provides structural info via proton or carbon signals.
• Mass Spectrometry: Determines molecular weight and structure.
• Elemental Analysis: Confirms molecular formula via C, H, N percentages.

Quick Reference Table

Technique	Principle	Application
Crystallisation	Dissolve in hot solvent, cool to crystallise	Purify solids like benzoic acid
Simple Distillation	Boiling point difference > 25°C	Separate ethanol from water
Column Chromatography	Differential adsorption on stationary phase	Separate plant pigments
IR Spectroscopy	Absorption of IR by functional groups	Identify C=O, O-H bonds
NMR Spectroscopy	Resonance of nuclei in magnetic field	Determine C-H framework
Mass Spectrometry	Ionisation and mass-to-charge ratio	Find molecular weight

Advice

Purification and Characterisation Quick Tips

• Crystallisation: Use minimum hot solvent for best yield.
• Distillation: Fractional for close boiling points (<25°C difference).
• Chromatography: Adjust solvent polarity for better separation.
• IR Spectroscopy: Look for characteristic peaks (e.g., 1700 cm⁻¹ for C=O).
• NMR: Use integration and splitting to deduce structure.

Purification and Characterisation Speed Quiz

Test your speed with 5 purification and characterisation questions! You have 30 seconds per question.