Separation Techniques

Methods of Separating Mixtures Magnet Filter Decant Evaporation Centrifuge Distillation

Filtration separates a liquid from a solid Zumdahl, Zumdahl, DeCoste, World of Chemistry  2002, page 40 Mixture of solid and liquid Stirring rod Filtrate (liquid component of the mixture) Filter paper traps solid Funnel

Distillation Copyright © 2007 Pearson Benjamin Cummings. All rights reserved.

Setup to heat a solution Zumdahl, Zumdahl, DeCoste, World of Chemistry  2002, page 42 Ring stand Beaker Wire gauze Ring Bunsen burner

long spout helps vapors to condense mixture for distillation placed in here Furnace Glass retort A Hero’s Fountain Eyewitness Science “Chemistry”, Dr. Ann Newmark, DK Publishing, Inc., 1993, pg 13

A Distillation Apparatus liquid with a solid dissolved in it thermometer condenser tube distilling flask pure liquid receiving flask hose connected to cold water faucet Dorin, Demmin, Gabel, Chemistry The Study of Matter, 3 rd Edition, 1990, page 282

Cooling water out Cooling water in Run hose into sink Connect hose to cold water tap

The solution is boiled and steam is driven off. Zumdahl, Zumdahl, DeCoste, World of Chemistry  2002, page 39

Salt remains after all water is boiled off. Zumdahl, Zumdahl, DeCoste, World of Chemistry  2002, page 39

No chemical change occurs when salt water is distilled. Zumdahl, Zumdahl, DeCoste, World of Chemistry  2002, page 40 Saltwater solution (homogeneous mixture) Distillation (physical method) Salt Pure water

Separation of a sand-saltwater mixture. Zumdahl, Zumdahl, DeCoste, World of Chemistry  2002, page 40

Centrifugation Spin sample very rapidly: denser materials go to bottom (outside) Separate blood into serum and plasma –Serum (clear) –Plasma (contains red blood cells ‘RBCs’) Check for anemia (lack of iron) Blood RBC’s Serum A B C AFTER Before

Electrolysis

Water Molecules Zumdahl, Zumdahl, DeCoste, World of Chemistry  2002, page 8

The decomposition of two water molecules. 2 H 2 O  O H2H2 Electric current Water molecules Diatomic oxygen molecule hydrogen molecules +

Electrolysis *Must add acid catalyst to conduct electricity *H 1+ water oxygen hydrogen “electro” = electricity “lysis” = to split Zumdahl, Zumdahl, DeCoste, World of Chemistry  2002, page 32 Water Hydrogen gas forms Oxygen gas forms ElectrodeSource of direct current H 2 O(l) O 2 (g) + 2 H 2 (g)

Reviewing Concepts Reviewing Concepts Physical Properties List seven examples of physical properties. Name three processes that are used to separate mixtures. Explain why sharpening a pencil is an example of a physical change. What allows a mixture to be separated by distillation?

Reviewing Concepts Reviewing Concepts Chemical Properties List three common types of evidence for a chemical change. How do chemical changes differ from physical changes? A pat of butter melts and then burns in a hot frying pan. Which of these changes is physical and which is chemical?