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Methods of Separating Mixtures
• Magnet
• Filter
• Decant
• Evaporation
• Centrifuge
• Chromatography
• Distillation
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Filtration separates
a liquid from a solid
Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 40
Mixture ofsolid andliquid Stirring
rod
Filtrate (liquidcomponentof the mixture)
Filter papertraps solid
Funnel
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Chromatography
• Tie-dye t-shirt
• Black pen ink
• DNA testing– Tomb of Unknown Soldiers– Crime scene – Paternity testing
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Separation by Chromatography
samplemixture
a chromatographic column
stationary phaseselectively absorbs
components
mobile phasesweeps sampledown column
detector
http://antoine.frostburg.edu/chem/senese/101/matter/slides/sld006.htm
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Separation by Chromatography
samplemixture
a chromatographic column
stationary phaseselectively absorbs
components
mobile phasesweeps sampledown column
detector
http://antoine.frostburg.edu/chem/senese/101/matter/slides/sld006.htm
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Ion chromatogram of orange juice
time (minutes)
de
tec
tor
res
po
ns
e
0 5 10 15 20 25
Na+
K+
Mg2+ Fe3+
Ca2+
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Setup to heat a solution
Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 42
Ring stand
Beaker
Wire gauze
Ring
Bunsen burner
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long spout helpsvapors to condense
mixture for distillation placed in here
Furnace
Glass retortA Hero’s Fountain
Eyewitness Science “Chemistry” , Dr. Ann Newmark, DK Publishing, Inc., 1993, pg 13ebooks.edhole.com
A Distillation Apparatus
liquid with a soliddissolved in it
thermometer
condenser
tube
distillingflask
pure liquid
receiving flaskhose connected to
cold water faucetDorin, Demmin, Gabel, Chemistry The Study of Matter , 3rd Edition, 1990, page 282ebooks.edhole.com
The solution is boiled and steam is driven off.
Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 39ebooks.edhole.com
Salt remains after all water is boiled off.
Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 39ebooks.edhole.com
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
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Separation of a sand-saltwater mixture.
Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 40ebooks.edhole.com
Separation of Sand from Salt1. Gently break up your salt-crusted sand with a plastic spoon.
Follow this flowchart to make a complete separation.
Salt-crusted
sand.
Dry
sand.
Wetsand.
Weigh themixture.
Decant clearliquid.
Evaporateto
dryness.
Pour intoheat-resistant
container.
Fill with water.
Stir and letsettle 1 minute.
Weighsand.
Calculateweight of
salt.
Repeat3 times?
Yes
No
2. How does this flowchart insure a completeseparation?
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Four-stroke Internal Combustion Engine
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Different Types of Fuel Combustion
2 C8H18 + 25 O2 16 CO2 + 18 H2O
__CH3OH +__O2 __CO2 +__H2O
Methanol (in racing fuel)
Gasoline (octane)
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Combustion Chamber
-The combustion chamber is the area where compression and combustion take place.
-Gasoline and air must be mixed in the correct ratio.
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•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
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•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
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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
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Water Molecules
Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 8ebooks.edhole.com
The decomposition of two water molecules.
2 H2O O2 + 2 H2
Electriccurrent
Watermolecules
Diatomic Diatomicoxygen molecule hydrogen molecules+
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Electrolysis
*Must add acid catalyst to conduct electricity
*H1+
water oxygen hydrogen
“electro” = electricity “lysis” = to split
Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 32
Water
Hydrogengas forms
Oxygengas forms
ElectrodeSource ofdirect current
H2O(l) O2 (g) + 2 H2 (g)
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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 -
hydrogengas
cathode
oxygengas
anode
D.C. powersource
water
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Reviewing ConceptsReviewing 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?
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Reviewing ConceptsReviewing ConceptsPhysical Properties
• Explain why sharpening a pencil is an example of a physical change.
• What allows a mixture to be separated by distillation?
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Reviewing ConceptsReviewing 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?
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Reviewing ConceptsReviewing 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?
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