Grade 7 Science
Pure Substances and Mixtures
Ms. Willis
Learning Goals / Success Criteria
 I can describe the processes used to separate solutions
into their components and identify some industry
applications of these processes.
 Vocabulary: evaporate, evaporation, distillation
Particles of Solutions
 Recall that solutions are mixtures in
which the particles of the different
components are so completely mixed
that the mixture appears to be a single
substance.
 E.g.: Salt water in the ocean…..
How can we separate Solutions?
1. Evaporation
2. Distillation
Evaporation
 Definition: the process by which a sample of
matter changes from a liquid to a gas. The solid
(or a more concentrated solution) is left behind.
 Evaporation is often used to remove the liquid
from a solution made of a liquid and a solid.
Evaporation
 Maple syrup is made by
boiling the sap which
evaporates the water and
leaves the concentrated
solution (syrup) or sugar
behind.
 Releasing water vapor into
the air is not harmful,
however, burning fossil
fuels to make the heat can
be polluting.
Distillation
 Definition: the process of separating liquids in a
solution by heating the solution, trapping and cooling
the gas, and collecting the resulting pure liquid.
 Short video to illustrate:
 https://www.youtube.com/watch?v=xxNfJLMNS4E
 If you had a liquid solution with more than two liquid
components, you could repeat the distillation process
to separate all the liquid parts of the solution and use a
different collecting flask for each component.
Distillation
Distillation
 Picture of a seawater distillation plant: (Seawater must
go through several stages to become drinking water.)
Distillation
 New technologies are going beyond simple distillation
for “desalinating” water:
 A closer look at desalinating seawater:
 https://www.youtube.com/watch?v=aysj7696b0A