SChem Sep Tech Concepts
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Transcript of SChem Sep Tech Concepts
Separation Techniques
Key Concepts
Solid + Solid (magnetic)
• Use magnet
Solid + Solid (pressure changes)
• Pressure changes affect change in state.
• No liquid state in some substances at sea-level pressure (sublimation)
• Eg: mothballs (napthalene)
• Can use to separate mixtures
Solid CO2
Heavy solid + Liquid
• Decanting
• Pour liquid out, leaving solid behind in test-tube/beaker/conical flask etc
• Not good method to purify
Small solids + Liquid• Use filtration
• Filter paper, filter funnel, beaker/conical flask
• Note: Not everything can be filtered out. Depends on size of pores (“holes”) in filter paper
Solid (dissolve in water) + Liquid
• Eg: Sugar, salt
• Crystallisation
• Evaporate extra water in mixture. Let crystals form naturally.
Liquid + Liquid (can mix)
• Distillation AND fractional distillation
• Check boiling points of liquid first
• Different boiling point (more than 100C difference) => Distillation
• Miscible = Mix
Liquid + Liquid (Cannot mix)
• Eg: Water + Oil
• Immiscible = Cannot mix
• Separating funnel is used
Check how pure is substance
• Chromatography
• Separate parts of mixture using suitable liquid (solvent-dissolve solid or liquid) and solid (normally paper)
Solid + Solid
• Example: Salt + Sand
• How to get