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?