separation technique

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

2. 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

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
time (minutes)
detector
response
0 5 10 15 20 25
Na+
K+
Mg2+ Fe3+
Ca2+

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

10. 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

11. 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 , 3rd Edition, 1990, page 282

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

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

14. 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

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

16. 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?

17. Four-stroke Internal
Combustion Engine

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

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. •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

21. •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

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)
Blood
RBC’s
Serum
A B C
AFTER
Before

23. Water Molecules
Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 8

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

25. 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
Hydrogen
gas forms
Oxygen
gas forms
Electrode
Source of
direct current
H2O(l) O2 (g) + 2 H2 (g)

26. 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 -
hydrogen
gas
cathode
oxygen
gas
anode
D.C. power
source
water

27. 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?

28. 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?

29. 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?

30. 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?