Methods of Separating Mixtures

1. Methods of Separating Mixtures • Magnet • Filter • Decant • Evaporation • Centrifuge • Chromatography • Distillation

2. Mixture of solid and liquid Stirring rod Funnel Filter paper traps solid Filtrate (liquid component of the mixture) Filtration separates a liquid from a solid Zumdahl, Zumdahl, DeCoste, World of Chemistry2002, page 40

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

5. Paper Chromatography

6. Separation by Chromatography sample mixture a chromatographic column stationary phase selectively absorbs components mobile phase sweeps sample down column detector http://antoine.frostburg.edu/chem/senese/101/matter/slides/sld006.htm

7. Separation by Chromatography sample mixture a chromatographic column stationary phase selectively absorbs components mobile phase sweeps sample down column detector http://antoine.frostburg.edu/chem/senese/101/matter/slides/sld006.htm

8. Ion chromatogram of orange juice K+ detector response Na+ Mg2+ Fe3+ Ca2+ 0 5 10 15 20 25 time (minutes)

9. Ring stand Beaker Wire gauze Ring Bunsen burner Setup to heat a solution Zumdahl, Zumdahl, DeCoste, World of Chemistry2002, page 42

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

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

12. The solution is boiled and steam is driven off. Zumdahl, Zumdahl, DeCoste, World of Chemistry2002, page 39

13. Salt remains after all water is boiled off. Zumdahl, Zumdahl, DeCoste, World of Chemistry2002, page 39

14. Distillation (physical method) Salt Pure water Saltwater solution (homogeneous mixture) No chemical change occurs when salt water is distilled. Zumdahl, Zumdahl, DeCoste, World of Chemistry2002, page 40

15. Separation of a sand-saltwater mixture. Zumdahl, Zumdahl, DeCoste, World of Chemistry2002, page 40

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

17. Four-stroke Internal Combustion Engine

18. Different Types of FuelCombustion Gasoline (octane) 2 C8H18 + 25 O2  16 CO2+ 18 H2O Methanol (in racing fuel) __CH3OH +__O2 __CO2 +__H2O

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

20. The Advantages of Methanol - Burning Engines • 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.

21. A Race Car - Basic Information • 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.

22. 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) AFTER Before Blood Serum RBC’s A B C

23. Water Molecules Zumdahl, Zumdahl, DeCoste, World of Chemistry2002, page 8

24. Diatomic Diatomic oxygen molecule hydrogen molecules + The decomposition of two water molecules. Water molecules Electric current 2 H2O  O2 + 2 H2

25. Water Oxygen gas forms Hydrogen gas forms H2O(l) O2 (g) + 2 H2 (g) Source of direct current Electrode Electrolysis “electro” = electricity “lysis” = to split *H1+ water oxygen hydrogen *Must add acid catalyst to conduct electricity Zumdahl, Zumdahl, DeCoste, World of Chemistry2002, page 32

26. D.C. power source oxygen gas hydrogen gas anode cathode water Electrolysis of Water Half reaction at the cathode (reduction): 4 H2O + 4 e - 2 H2 + 4 OH 1- Half reaction at the anode (oxidation): 2 H2O  O2 + 4 H 1+ + 4 e -

27. Reviewing ConceptsPhysical 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?

28. Reviewing ConceptsPhysical Properties • Explain why sharpening a pencil is an example of a physical change. • What allows a mixture to be separated by distillation?

29. Reviewing ConceptsChemical 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?

30. Reviewing ConceptsChemical 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?