Separation Techniques

Methods of Separating Mixtures Magnet Filter Decant Evaporation Centrifuge Chromatography 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

Casein Glue - Activity Keys Casein Glue Activity Casein Glue Activity keykey

Chromatography Tie-dye t-shirt Black pen ink DNA testing –Tomb of Unknown Soldiers –Crime scene –Paternity testing

Paper Chromatography

Separation by Chromatography sample mixture a chromatographic column stationary phase selectively absorbs components mobile phase sweeps sample down column detector

Separation by Chromatography sample mixture a chromatographic column stationary phase selectively absorbs components mobile phase sweeps sample down column detector

Ion chromatogram of orange juice time (minutes) detector response Na + K+K+ Mg 2+ Fe 3+ Ca 2+

Chromatography KeysKeys

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

Separation of Sand from Salt 1.Gently break up your salt-crusted sand with a plastic spoon. Follow this flowchart to make a complete separation. Salt- crusted sand. Dry sand. Wet sand. Weigh the mixture. Decant clear liquid. Evaporate to dryness. Pour into heat-resistant container. Fill with water. Stir and let settle 1 minute. Weigh sand. Calculate weight of salt. Repeat 3 times? Yes No 2.How does this flow chart insure a complete separation?

Four-stroke Internal Combustion Engine

Different Types of Fuel Combustion 2 C 8 H O 2  16 CO H 2 O __CH 3 OH +__O 2  __CO 2 +__H 2 O Methanol (in racing fuel) Gasoline (octane)

Combustion Chamber -The combustion chamber is the area where compression and combustion take place. -Gasoline and air must be mixed in the correct ratio.

Methanol can run at much higher compression ratios, meaning that you can get more power from the engine on each piston stroke. Methanol provides significant cooling when it evaporates in the cylinder, helping to keep the high-revving, high- compression engine from overheating. Methanol, unlike gasoline, can be extinguished with water if there is a fire. This is an important safety feature. The ignition temperature for methanol (the temperature at which it starts burning) is much higher than that for gasoline, so the risk of an accidental fire is lower. The Advantages of Methanol - Burning Engines

At 900 hp, it has about two to three times the horsepower of a "high- performance" automotive engine. For example, Corvettes or Vipers might have 350- to 400-horsepower engines. At 15,000 rpm, it runs at about twice the rpm of a normal automotive engine. Compared to a normal engine, an methanol engine has larger pistons and the pistons travel a shorter distance up and down on each stroke. The motor is lighter. This lowers their inertia and is another factor in the high rpm. A Race Car - Basic Information

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)

Electrolysis of Water Half reaction at the cathode (reduction): 4 H 2 O + 4 e -  2 H OH 1- Half reaction at the anode (oxidation): 2 H 2 O  O H e - hydrogen gas cathode oxygen gas anode D.C. power source water

Reviewing Concepts Reviewing Concepts Physical Properties List seven examples of physical properties. Describe three uses of physical properties. Name two processes that are used to separate mixtures. When you describe a liquid as thick, are you saying that it has a high or low viscosity?

Reviewing Concepts Reviewing Concepts Physical Properties 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 Under what conditions can chemical properties be observed? List three common types of evidence for a chemical change. How do chemical changes differ from physical changes?

Reviewing Concepts Reviewing Concepts Chemical Properties Explain why the rusting of an iron bar decreases the strength of the bar. A pat of butter melts and then burns in a hot frying pan. Which of these changes is physical and which is chemical?