Purification and Characterisation of Organic Compounds: One-Page Formula Sheet

Purification and Characterisation of Organic Compounds — formula sheet

Formulas

• % C = (12/44) × (mass of CO₂ / mass of compound) × 100
• % H = (2/18) × (mass of H₂O / mass) × 100
• Kjeldahl: % N = 1.4 × N × V / mass
• Carius: % X from mass of AgX

Key ideas

• Steam distillation for steam-volatile, water-immiscible compounds
• Lassaigne's test converts N, S, halogens to ionic forms
• Rf value = distance by compound / distance by solvent
• Kjeldahl method is not used for nitro, azo or ring nitrogen

Traps to avoid

• Using Kjeldahl for nitrobenzene
• Mixing up which method separates which mixture
• Arithmetic errors in percentage composition

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