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Lyophilic Sols
"Solvent-loving" • ReversiblePure Water
Add starch or gelatin
Properties:
- • Self-stabilizing (no stabilizer needed)
- • High viscosity
- • Reversible (reforms after evaporation)
- • Weak Tyndall effect
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Lyophobic Sols
"Solvent-fearing" • IrreversiblePure Water
Add FeCl₃ or As₂O₃
Properties:
- • Requires stabilizing agent
- • Low viscosity
- • Irreversible (cannot reform)
- • Strong Tyndall effect
Safety Precautions
- Arsenic compounds are highly toxic (As₂O₃ and As₂S₃): arsenic(III) oxide is a potent poison and recognised carcinogen. Work only in a fume cupboard, never pipette by mouth, wear gloves, and collect all arsenic-containing waste separately for hazardous disposal.
- Hydrogen sulphide (H₂S) is toxic and flammable: it paralyses the sense of smell, so a fading "rotten-egg" odour does not mean the air is safe. Generate and pass H₂S only in a fume cupboard.
- Ferric chloride (FeCl₃) is corrosive and staining: its solution is acidic and stains skin and clothing — wear gloves and eye protection.
- Boiling water and hot glassware: the Fe(OH)₃ sol is made by adding FeCl₃ dropwise to actively boiling water. Add slowly to avoid spurting and handle hot beakers with tongs.
- Use distilled water: electrolytes in tap water can coagulate a lyophobic sol before you can test it.
Predict Before You Test
Prepare one lyophilic sol and one lyophobic sol above, then predict how they will differ. The comparison tests stay locked until you lock a prediction.
🔬 Perform Tests
Lab Notebook
Observations will appear here...