Unit 2, Lesson 4: Separation Methods (Part 2)

Recrystallization Separation of impurities from a solid sample by preparing a saturated solution, then slowly evaporating off the liquid to leave behind pure crystals of the solid. 10 min

Gravity Separation Separation of a solid from a mechanical mixture, based on its density. 10 min

Chromatography Separation of small amounts of solutions by allowing a solvent to absorb up a column (e.g. paper), carrying the solutes with it, and causing them to separate based on their different dissolving tendencies.

Brain Break!

Chemical and Physical Changes A chemical change is a change in which new substances are formed. A physical change is a change in the phase of a substance, such that no new substances are formed. Note: chemical changes are often accompanied by physical changes. If a change is said to be chemical, it means that the primary change is chemical. Brainstorm some examples as a class, Scattergories style (teams of three, three minutes to write) – 25 min

Homework: On separation methods: pg. 59 #47, 48, 54, and 57 On chemical and physical changes: pg. 61 #59 5 min