Grade 7 Science Separating Solutions
Student Activity: Discuss with a partner how you would separate the following mixtures… • Salt water • Muddy water • Nuts and bolts
Iron filings and sand • Vegetable oil and sand • Vegetable oil and water • Salt and pepper Be prepared to defend your answers!
Discussion Question “Are the components you have separated still mixtures, or are they pure? Why or why not?”
Separation Techniques Mechanical Sorting: • Used to separate the parts of a mixture based on properties such as particle size. • Examples: floatation & magnetism
Filtration: • A common way to separate solid particles from a mixture • The filters can have holes of varying sizes… small to microscopic.
Oil filter Coffee filter Colander Furnace filter
Evaporation: • Change of state from a liquid to a gas. • Used to recover a solid solute from a solution.
Distillation: • Uses two changes of state: evaporation and condensation. • It allows you to recover BOTH the solute and solvent from a solution.
Paper Chromatography: • Used to separate the colored substances in a mixture such as ink. • Used to separate the solvents in a mixture.
Separation Techniques in the Home: • Colanders • Clothes dryers • Window screens • Coffee percolators • Salad spinners Any others?