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