Applied Chemistry: Classifying Mixtures, Solutes, and Physical Separation Methods
In our environment, most substances do not exist in pure form but as mixtures. A 'mixture' is a physical blend of two or more substances that are not chemically combined, each retaining its original individual properties, and they can be separated by physical methods (such as vegetable salad, sand and water, or saltwater). In contrast, a 'compound' results from chemical bonding where elements lose their individual identities to form a totally new substance. In this lesson, students explore physical separation techniques: filtration (for insoluble solids), evaporation (for dissolved solids), magnetic attraction (for iron), and flotation.
🧪 Physical Separation Techniques
Filtration
Separates insoluble solids from liquids using filter paper (e.g., separating sand from water).
Evaporation
Separates a soluble solid from a liquid by boiling away the liquid (e.g., harvesting sea salt).
Magnetic Attraction
Uses a magnet to pull out magnetic substances (like iron filings) from non-magnetic sand.
Flotation & Settling
Uses density differences (e.g., sawdust floats while dense pebbles sink to the bottom).
How can you separate a mixture of sand, salt, and water?
Procedure: 1) Pour the mixture through filter paper: sand stays on the paper (filtration); 2) Heat the remaining saltwater until all water evaporates, leaving pure salt crystals behind (evaporation).
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