GRADE 7 SCIENCE - WikispacesTechniques... · the following mixtures… ! Salt water ! Muddy water !...
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Transcript of GRADE 7 SCIENCE - WikispacesTechniques... · the following mixtures… ! Salt water ! Muddy water !...
GRADE 7 SCIENCE
Separation Techniques
Discuss with a partner how you would separate the following mixtures…
Ø Salt water Ø Muddy water Ø Nuts and bolts Ø Iron filings and sand
Ø Vegetable oil and sand
Ø Vegetable oil and water
Ø 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?
SEPARATING MECHANICAL
MIXTURES
Sorting ¢ separa'ng substances based on appearance (colour, size, texture)
¢ some recycling programs require the driver to separate glass, plas'c, and paper
Floatation and Settling ¢ allow heavier materials to se=le to the bo=om of a liquid and extract them with a tool
¢ if a substance is light enough, it will float to the top of a liquid and a tool can be used to skim it from the surface
Sifting ¢ separa'ng solids by size
¢ involves passing solid materials through a screen or mesh
¢ parts that are small enough to pass through are separated from larger ones that can’t fit through
¢ different than filtra'on � filtra'on is used to separate solids from liquids or gases � siCing separates solids from other solids
MAGNETISM ¢ some metals are magne'c because their component par'cles are a=racted to the par'cles within magnets
¢ A magnet can be used to separate magne'c materials (iron, steel) from others (plas'c dashboards, rubber 'res)
SEPARATING SOLUTIONS
Filtration ¢ separa'ng solids from liquids or gases
¢ when solu'on is poured through filter, solid parts are trapped, and liquid or gas pass through
¢ if the solid is small enough, it may s'll pass through the filter
¢ ex: salt dissolved in water
Coffee filter Oil filter
Furnace filter Colander
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.
¢ Solution is boiled, which vaporizes the solvent and separates it from the solute
¢ Gas condenses on a cool surface and is collected
INDUSTRIAL DISTILLATION TOWER
SEPARATION TECHNIQUES IN THE
HOME: ¢ Colanders ¢ Clothes dryers ¢ Window screens ¢ Coffee percolators ¢ Salad spinners Any others?
SEPARATION TECHNIQUES IN
INDUSTRY: ¢ Colanders ¢ Clothes dryers ¢ Window screens ¢ Coffee percolators ¢ Salad spinners Any others?