Transcript Document

Általános Kémiához ábrák, etc.
2006. ősz
2004. őszi tételsor az ElmKém web-oldalán:
www.chem.elte.hu/departments/elmkem/fg/oktatas/altkem
(40 + tétel; főbb fejezetek:)
Alapfogalmak
A gázhalmazállapot
A reakciók energetikája (termokémia)
A termodinamika alapjai, a folyamatok iránya, egyensúly
Halmazállapotok és fizikai tulajdonságok
Elektrokémia
Reakciókinetika
Az anyag atomi - molekuláris szerkezete.
Atomok elektronszerkezete és a periódusos rendszer
A kémiai kötés
A kémia felosztása különböző lehet
Egy könyvkiadó: WileyEurope > Chemistry
Browse Chemistry subjects
Analytical Chemistry
Industrial Chemistry
Biochemistry
Inorganic Chemistry
Chemical Engineering
Organic Chemistry
Computational Chemistry
& Molecular Modeling
Physical Chemistry
Polymer Science & Technology
Electrochemistry
Special Topics
Environmental Chemistry
Spectroscopy
General Chemistry
Kémia mindenhol
TOP 50 CHEMICALS:
Rank
1995
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
1994
1
2
3
4
5
6
7
8
10
9
11
18
14
12
13
16
Billions of lb
1995
1994
Sulfuric acid
95.36 89.63
Nitrogen
68.04 63.91
Oxygen
53.48 50.08
Ethylene
46.97 44.60
Lime(b)
41.23 38.37
Ammonia
35.60 34.51
Phosphoric acid
26.19 25.58
Sodium hydroxide
26.19 25.11
Propylene
25.69 23.94
Chlorine
25.09 24.37
Sodium carbonate(c)
22.28 20.56
Methyl tert-butyl ether 17.62 13.61
Ethylene dichloride
17.26 16.76
Nitric acid
17.24 17.22
Ammonium nitrate(d)
15.99 17.03
Benzene
15.97 15.27
22
20
Carbon dioxide(f)
10.89
11.80
27
26
Hydrochloric acid
7.33
7.47
33
33
Acetic acid
4.68
3.98
42
43
42
43
Titanium dioxide
Acetone
2.77
2.76
2.76
2.66
50
49
Bisphenol A
1.62
1.70
Top 50 Chemical Companies in 1999
Rank
Rank
1999 1998
Company
Total sales
Company
Chemical sales
Chemical operating profits
Total sales
1999 ($ M)
Chemical sales
1999 ($ M) % of
total
Chem. Oper. profits
1999 ($ M) %
1
2
3
4
5
6
7
8
9
10
11
12
13
1
2
3
4
8
6
5
19
35
11
28
10
13
BASF (Germany)
DuPont (U.S.)
Bayer (Germany)
Dow Chemical (U.S.)
Exxon Mobil (U.S.)b
ICI (U.K.)
Shell (U.K./Netherlands)
Akzo Nobel (Netherlands)
Degussa-Hüls (Germany)c
BP Amoco (U.K.)
Total (France)c 42,069.0
Elf Aquitaine (France)
Sumimoto Chemical (Japan)
34,689.4
29,740.0
29,106.7
18,929.0
185,527.0
13,671.5
149,706.0
15,375.9
13,157.7
101,180.0
9,343.6
37,872.8
8,342.9
31,250.3
27,688 .0
20,192.5
18,600.0
13,777.0
13,671.5
12,886.0
12,323.5
10,085.8
9,392.0
22.2
9,272.2
8,136.5
90.1%
93.1
69.4
98.3
7.4
100.0
8.6
80.1
76.7
9.3
643.5
24.5
97.5
1,350.9
2,961.0
3,024.7
2,732.0
1,354.0
923.9
885.0
819.3
544.6
1,100.0
6.9
540.2
588.9
4.3
10.7
15.0
14.7
9.8
6.8
6.9
6.6
5.4
11.7
16
18
Henkel (Germany)
12,104.0
7,324.6
60.5
604.1
8.2
Nemzeti jövedelmekhez hasonlítva:
Comparative economic indicators, 2000
Hungary Slovenia
GDP (US$ bn)
45.6
18.1
GDP per head (US$ at PPP) 9,035
14,250
Slovakia
19.2
8,718
5.8
7.2
March 12, 2002 : The survey, published in a recent issue of the Society's publication, Chemical
& Engineering News (C & EN), ranks the global top 50 by their chemical sales. It also charts
their total sales, chemical operating profits and capital spending
The Consumer Law Page: Articles:
http://consumerlawpage.com/article/household-chemicals.shtml
TOP "10" HAZARDOUS HOUSEHOLD CHEMICALSBy Richard Alexander
AIR FRESHENERS: Most air fresheners interfere with your ability to smell by coating your
nasal passages with an oil film, or by releasing a nerve deadening agent. Known toxic
chemicals found in an air freshener: Formaldehyde: Highly toxic, known carcinogen. Phenol:
When phenol touches your skin it can cause it to swell, burn, peel, and break out in hives. Can
cause cold sweats,convulsions, circulatory collapse, coma and even death.
AMMONIA: It is a very volatile chemical, it is very damaging to your eyes, respiratory tract
and skin.
BLEACH: It is a strong corrosive. It will irritate or burn the skin, eyes and respiratory tract. It
may cause pulmonary edema or vomiting and coma if ingested. WARNING: never mix bleach
with ammonia it may cause fumes which can be DEADLY.
DISHWASHER DETERGENTS: Most products contain chlorine in a dry form that is highly
concentrated.# 1 cause of child poisonings, according to poison control centers.
DRAIN CLEANER: Most drain cleaners contain lye, hydrochloric acid or trichloroethane.
Lye: Caustic, burns skin and eyes, if ingested will damage esophagus and stomach.
Hydrochloric acid: Corrosive, eye and skin irritant, damages kidneys, liver and digestive tract.
Trichloroethane: Eye and skin irritant, nervous system depressant; damages liver and kidneys.
contnd,.
FURNITURE POLISH: Petroleum Distillates: Highly flammable, can cause skin and
lung cancer. Phenol: (see Air fresheners, Phenol.) Nitrobenzene: Easily absorbed through
the skin, extremely toxic.
MOLD AND MILDEW CLEANERS: Chemicals contained are: Sodium hypochlorite:
Corrosive, irritates or burns skin and eyes, causes fluid in the lungs which can lead to coma
or death. Formaldehyde: Highly toxic, known carcinogen. Irritant to eyes, nose, throat, and
skin. May cause nausea, headaches, nosebleeds, dizziness, memory loss and shortness of
breath.
OVEN CLEANER: Sodium Hydroxide (Lye): Caustic, strong irritant, burns to both skin
and eyes. Inhibits reflexes, will cause severe tissue damage if swallowed.
ANTIBACTERIAL CLEANERS: may contain: Triclosan: Absorption through the skin
can be tied to liver damage.
LAUNDRY ROOM PRODUCTS: Sodium or calcium hypocrite: Highly corrosive,
irritates or burns skin, eyes or respiratory tract. Linear alkylate sulfonate: Absorbed through
the skin. Known liver damaging agent. Sodium Tripolyphosphate: Irritates skin and mucous
membranes, causes vomiting. Easily absorbed through the skin from clothes.
TOILET BOWL CLEANERS: Hydrochloric acid: Highly corrosive, irritant to both skin
and eyes. Damages kidneys and liver. Hypochlorite Bleach: Corrosive, irritates or burns
eyes, skin and respiratory tract. May cause pulmonary edema, vomiting or coma if ingested.
Contact with other chemicals may cause chlorine fumes which may be fatal
VÁLOGATÁSOK KURRENS EREDMÉNYEKBŐL:
September 6, 2004
Vol. 82, Iss. 36
INHIBITORS TARGET KEY TB ENZYME
Iminosugars may provide leads for new class of tuberculosis drugs
Scientists in England have designed and synthesized
the first inhibitors of an enzyme that is essential for
the survival of the tuberculosis bacterium [Org.
Biomol. Chem., 2, 2418 (2004)]. The compounds
might lead to better treatments for TB, which annually
infects 8 million to 10 million people and kills 2
million to 3 million. e and kills 2 million to 3 million.
SCIENCE & TECHNOLOGY
RDX LINKS RUSSIAN CRASHES
Powerful explosive found in the debris of two planes
that crashed
Traces of RDX, a common military explosive
that is also known as hexogen or cyclonite,
were found at the crash sites of two Russian
planes that went down within minutes of
each other on Aug. 24, Russian authorities
report. RDX was also used in a suicide
bombing at a Moscow metro station on Aug.
31, news reports say.
"RDX is a very powerful explosive," says
Jimmie C. Oxley, a professor of chemistry at
the University of Rhode Island. "A terrorist
wouldn't need to conceal very much." RDX
has an explosive power considerably greater
than that of TNT, is chemically stable, and is
more susceptible than TNT to shock
detonation.
"Molekuláris giroszkóp"
COMPOSITE MATERIALS
Custom blending of materials with distinct
characteristics leads to advanced composites with tailormade properties
IT'S A BIRD, IT'S A PLANE ... Advanced composite materials in the V22 Osprey's tilt-rotor system play a key role in enabling the
sophisticated plane to take off and land on aircraft carriers like a
helicopter and fly like a turboprop airplane.
SHEET MOLDING Sheets of a composite molding material can be prepared by
feeding glass or carbon fibers (chopped or intact) and a polymer-based resin
(orange trough) between a pair of plastic films
Gyönyörűszép Molekulák
One example, reported by Bryan W. Eichhorn's group at the University of Maryland, is the
[As@Ni12@As20]3– ion. This cluster consists of an As20 pentagonal dodecahedron that encapsulates a Ni12
icosahedron, which contains an arsenic atom at its center. The As20 cage is related to the smallest fullerene, C20
5, 2003
C&EN May
Source: C&EN/ April 14, 2003
MOLECULAR DESIGN
ION RECOGNITION
System exploits weak interactions to attract anion to cation in capsule
A new approach to anion recognition that uses electrostatic and hydrogenbonding interactions has been developed by chemists at the University of
Missouri, Columbia.
"For the first time, we have utilized a single molecule to completely
encapsulate an ion pair in polar media," chemistry professor Jerry L.
Atwood tells C&EN. "We envision that resins incorporating these capsules
could be used in anion sensing in environmental applications."
Atwood and postdoc Agnieszka Szumna embedded a
tetramethylammonium cation in the pocket of a resorcin[4]arene molecule
functionalized with bulky amide substituents. The complex selectively
binds to a chloride anion in solvents such as methanol [Chem. Comm.,
2003, 940].
Ezt is tudjuk ……
EPO
Understanding the function of endogenous
hormones and putting them to good use to
treat diseases has been one of the great
accomplishments of modern medicine. One
natural hormone that has turned out to be a
blockbuster drug--but not without some
controversy--is erythropoietin (EPO).
EPO is a glycoprotein (protein-sugar conjugate) that serves as the
primary regulator of red blood cells (erythrocytes) in mammals. It
stimulates bone marrow stem cells to differentiate into red blood cells
and controls hemoglobin synthesis and red blood cell concentration.
Human EPO is a 30,400-dalton molecule containing 165 amino acids
and four carbohydrate chains that incorporate sialic acid residues.
There are several forms of EPO, designated by Greek letters, that
differ only in the carbohydrate content.
In infants, EPO is produced mostly in the liver, but the kidneys become the primary site of EPO synthesis
shortly after birth. EPO production is stimulated by reduced oxygen content in arterial blood in the kidneys.
Circulating EPO binds to receptors on the surface of erythroid progenitor cells that in turn mature into red blood
cells.….. contnd
Human EPO was first isolated and later purified from urine in the
1970s. Interest in developing clinical uses for EPO led to the
discovery of the gene encoding EPO, and several groups devised
recombinant DNA methods to produce EPO by the mid-1980s.
Recombinant EPO quickly made it to market to treat anemia resulting
from a host of conditions, primarily kidney failure, HIV infection in
patients treated with AZT, and cancer chemotherapy. Doses of EPO
are given by injection one or more times per week to maintain a
normal hematocrit level, the ratio of red blood cell volume to total
blood volume. Generally, EPO might be prescribed for any condition
where blood oxygen levels are depressed and to help eliminate the
potential need for blood transfusions.
……
Enzyme immunoassays can provide a measure of serum EPO levels,
but the tests can't determine if the EPO is natural or produced
recombinantly and injected by unscrupulous athletes. The World
Anti-Doping Agency has now developed combination urine and blood
tests that can detect EPO abuse by athlet.
Robert Boyle (1627–1691) was born at Lismore Castle, Munster,
Ireland, the fourteenth child of the Earl of Cork. As a young man of
means, he was tutored at home and on the Continent. He spent the
later years of the English Civil Wars at Oxford, reading and
experimenting with his assistants and colleagues. This group was
committed to the New Philosophy, which valued observation and
experiment at least as much as logical thinking in formulating
accurate scientific understanding. At the time of the restoration of the
British monarchy in 1660, Boyle played a key role in founding the Royal
Society to nurture this new view of science.
Although Boyle's chief scientific interest was chemistry, his first
published scientific work, New Experiments Physico-Mechanicall,
Touching the Spring of the Air and its Effects (1660), concerned the
physical nature of air, as displayed in a brilliant series of experiments
in which he used an air pump to create a vacuum. The second edition
of this work, published in 1662, delineated the quantitative
relationship that Boyle derived from experimental values, later
known as "Boyle's law": that the volume of a gas varies inversely
with pressure.
Robert Boyle at the age of thirty-seven, with his air pump in the background.
François Diodati reengraved this image from an engraving by William Faithorne, Opera varia (1680).
Courtesy Edgar Fahs Smith Memorial Collection, Department of Special Collections, University of
Pennsylvania Library.
Boyle was an advocate of corpuscularism, a form of atomism
that was slowly displacing Aristotelian and Paracelsian views
of the world. Instead of defining physical reality and
analyzing change in terms of Aristotelian substance and form
and the classical four elements of earth, air, fire, and water—
or the three Paracelsian elements of salt, sulfur, and
mercury—corpuscularism discussed reality and change in
terms of particles and their motion. Boyle believed that
chemical experiments could demonstrate the truth of the
corpuscularian philosophy. In this context he defined the
term element in Sceptical Chymist (1661): " . . . certain
primitive and simple, or perfectly unmingled bodies; which
not being made of any other bodies, or of one another, are the
ingredients of which all those called perfectly mixt bodies are
immediately compounded, and into which they are ultimately
resolved."
Robert Boyle:
The Skeptical Chemist, 1661 (!)
"Én megpróbáltam a kémiát más szempontok szerint művelni,
nem úgy, ahogy az eddigi kémikusok tették, hanem ahogy egy
tudóshoz illik." ....
"Bár viselnék az emberek inkább a tudományok előrehaladását
szívükön, mint önző érdeküket, akkor könnyen belátnák, hogy
nagyobb szolgálatot tennének a világnak, ha minden erejüket
kísérletek végzésére és megfigyelések gyűjtésére fordítanák,
ahelyett hogy kísérleti alapozás nélküli elméleteket állítanának
fel. "
The Burning lenses
Calcination of a piece of metal with the burning lenses
Jövőre:
Joseph Louis Gay-Lussac’s law of combining volumes (1808) (when
two gases react, the volumes of the reactants and products—if gases—
are in whole number ratios) tended to support Dalton’s atomic theory.
Dalton did not in fact accept Gay-Lussac's work, but the Italian chemist
Amedeo Avogadro (1776–1856) saw it as the key to a better
understanding of molecular constituency.
Amedeo Avogadro.
In 1811 Avogadro hypothesized that equal volumes of gases at the same temperature and pressure contain equal
numbers of molecules. From this hypothesis it followed that relative molecular weights of any two gases are the
same as the ratio of the densities of the two gases under the same conditions of temperature and pressure. Avogadro
also astutely reasoned that simple gases were not formed of solitary atoms but were instead compound molecules of
two or more atoms. (Avogadro did not actually use the word atom; at the time the words atom and molecule were
used almost interchangeably. He talked about three kinds of "molecules," including an "elementary molecule"—what
we would call an atom.) Thus Avogadro was able to overcome the difficulty that Dalton and others had encountered
when Gay-Lussac reported that above 100oC the volume of water vapor was twice the volume of the oxygen used to
form it. According to Avogadro, the molecule of oxygen had split into two atoms in the course of forming water
vapor.
Curiously, Avogadro's hypothesis was neglected for half a century after it was first published. Many reasons for this
neglect have been cited, including some theoretical problems, such as Jöns Jakob Berzelius's "dualism," which
asserted that compounds are held together by the attraction of positive and negative electrical charges, making it
inconceivable that a molecule composed of two electrically similar atoms—as in oxygen—could exist. In addition,
Avogadro was not part of an active community of chemists: the Italy of his day was far from the centers of chemistry
in France, Germany, England, and Sweden, where Berzelius was based.
Avogadro was a native of Turin, where his father, Count Filippo Avogadro, was a lawyer and government leader in
the Piedmont (Italy was then still divided into independent countries). Avogadro succeeded to his father's title, earned
degrees in law, and began to practice as an ecclesiastical lawyer. After obtaining his formal degrees, he took private
lessons in mathematics and sciences, including chemistry. For much of his career as a chemist he held the chair of
physical chemistry at the University of Turin.
Avogadro EREDETI CIKKEBOL! : http://web.lemoyne.edu/~giunta/avogadro.html
A TELJES SZOVEGET FILE-BAN ELTETTEM: avogadro-original
Essay on a Manner of Determining the Relative Masses of the Elementary Molecules of Bodies, and the Proportions in
Which They Enter into These Compounds
Journal de Physique 73, 58-76 (1811) [Alembic Club Reprint No. 4] I.
M. Gay-Lussac has shown in an interesting Memoir (Mémoires de la Société d'Arcueil, Tome II.) that gases always unite in a very
simple proportion by volume, and that when the result of the union is a gas, its volume also is very simply related to those of its
components. But the quantitative proportions of substances in compounds seem only to depend on the relative number of
molecules which combine, and on the number of composite molecules which result. It must then be admitted that very simple
relations also exist between the volumes of gaseous substances and the numbers of simple or compound molecules which form
them. Kiemeles FG: The first hypothesis to present itself in this connection, and apparently even the only admissible one, is the
supposition that the number of integral molecules in any gases is always the same for equal volumes, or always proportional to
the volumes. Indeed, if we were to suppose that the number of molecules contained in a given volume were different for different
gases, it would scarcely be possible to conceive that the law regulating the distance of molecules could give in all cases relations as
simple as those which the facts just detailed compel us to acknowledge between the volume and the number of molecules. On the
other hand, it is very well conceivable that the molecules of gases being at such a distance that their mutual attraction cannot be
exercised, their varying attraction for caloric may be limited to condensing the atmosphere formed by this fluid having any greater
extent in the one case than in the other, and, consequently, without the distance between the molecules varying; or, in other words,
without the number of molecules contained in a given volume being different. Dalton, it is true, has proposed a hypothesis directly
opposed to this, namely that the quantity of caloric is always the same for the molecules of all bodies whatsoever in the gaseous
state, and that the greater or less attraction for caloric only results in producing a greater or less condensation of this quantity
around the molecules, and thus varying the distance between the molecules themselves. But in our present ignorance of the manner
in which this attraction of the molecules for caloric is exerted, there is nothing to decide us à priori in favour of the one of these
hypotheses rather than the other; and we should rather be inclined to adopt a neutral hypothesis, which would make the distance
between the molecules and the quantities of caloric vary according to unknown laws, were it not that the hypothesis we have just
proposed is based on that simplicity of relation between the volumes of gases on combination, which would appear to be otherwise
inexplicable.
Maxwell, around 1875, describing atoms:
"foundation stones of the material universe ...
unbroken and unworn. They continue to this day as
they were createdperfect in number and measure
and weigth."
(Scientific American, Aug. 1997, p. 73.)
Elektronsűrűség
a H-atomban
1s állapot
2s állapot
2pz állapot
3s állapot
Force Between Parallel Wires
If the currents are parallel, the
force is attractive.
If the currents are anti-parallel,
the force is repulsive.
PROTOTYPE The mass
of the international
kilogram artifact in
Paris may be changing.
REDEFINITION Ian Robinson, a fellow in electrical metrology at the
U.K.'s National Physical Laboratory, uses the watt balance to
determine values for the Planck constant. (NPL photographs: ©
Crown copyright 1999. Reproduced by permission of the Controller
of HMSO and the Queen's Printer for Scotland)
NPL PHOTO
Electronic Balance
http://www.sensorsmag.com/articles/0602/27/pf_main.shtml
Jean-Christophe Emery, Mettler Toledo GmbH
The most accurate electronic balances are based on electromagnetic
force restoration (EMFR), also called electromagnetic force
compensation. ….., one or more levers, and an electromagnetic system
that assumes the role of the weights in a two-pan scale balance.
Equilibrium is maintained by a control system incorporating an optical
position sensor.
.
When the coil’s force compensates the gravitational force exerted by an unknown mass, an optical sensor
detects a stable predefined zero position that indicates a state of equilibrium. Changing the ratio of the
levers allows forces smaller than 1 N to balance much bigger ones. Today it is common to have a system
with one, two, or even three levers, depending on the load range.
Higanyos manométer:
U.S. National Chemistry Olympiad
1995 National Test
An open-ended mercury manometer is used to measure the pressure exerted by a trapped gas as
shown in the figure. Atmospheric pressure is 749 mmHg. What is the pressure of the trapped gas?
Egy mai kereskedelmi higanyos manométer (olasz cég hirdetése)
http://www.imgc.to.cnr.it/english/aboutimgc/department/manometro.htm
The HG5 mercury manometer
The HG5 manometer is the primary
standard of IMGC for the barometric
pressure (100 Pa to 120 kPa) both in
absolute and gauge mode. Designed and
built at IMGC after long experimentation, it
is based on the old principle of
measurement used by Torricelli, that is to
say the atmospheric pressure is weighted
by a mercury column whose height is
measured.
HG5 is made by a glass U-tube, filled with
mercury up to half height and immersed in
a bath of termostated water, in which the
temperature is maintained constant at 20
°C. The dimensions of the two columns of
the U-tube are 1 m length , 60 mm internal
diameter; the differential mercury
displacement, (the column height) , from
the initial equilibrium position, ( that is the
“zero position”, with the same pressure in
both columns), is detected through a
“single beam” differential interferometer.
Farm Toxins: Mercury Manometer Replacement"
October 2, 2000 WPTZ NEWS CHANNEL 5
farms within the Vermont portion of the Lake Champlain Basin. Replacing mamometers will help prevent
mercury pollution in the basin and help protect the health of humans and animals on dairy farms.
Manometers are used by farmers to measure the proper working pressure
of milking systems. The Northwest Vermont Solid Waste Management District received $20,200
through the Lake Champlain Basin Program for this project. In partnership with the Vermont Department of
Agriculture, 42 out of 84 known mercury manometers have been replaced with non-mercury manometers so
far - at no cost to the farmers. Each manometer contains up to 1/2 pound of mercury. The mercury collected
will be disposed by a certified mercury handler.
.......
Bourdon-cső:
A szobai barométer
aneroid b.
KIS NYOMÁSOK MÉRÉSE
Pirani-vákuummérő
Elv: a gáz hővezető képessége nyomásától fógg
Pirani Gauges:
In a Pirani gauge (see above), two filaments (platinum alloy in the best gauges), act as
resistances in two arms of a Wheatstone bridge. The reference filament is immersed in a
fixed-gas pressure, while the measurement filament is exposed to the system gas
Még érzékenyebb az Ionizációs
Vákuummérő
Ionisations-Vakuummeter bestehen im allgemeinen aus drei Elektroden (Glühkathode, Anode und
Ionenfänger). Sie arbeiten bei niedrigen Spannungen und ohne äußeres Magnetfeld. Die Glühkathode ist
eine sehr ergiebige Elektronenquelle. Die Elektronen werden im elektrischen Feld (s. Abb. 4) beschleunigt
und nehmen aus dem Feld genügend Energie auf, um das Gas, in dem sich das Elektrodensystem
befindet, zu ionisieren. Die
gebildeten positiven Gasionen gelangen auf den bezüglich der
Kathode negativen Ionenfänger und geben hier ihre Ladung ab. Der dadurch entstehende Ionenstrom
ist ein Maß für die Gasdichte und damit für den Gasdruck
Térfogatmérés
eudiométer
piknométer
http://en.wikipedia.org/wiki/Peltier-Seebeck_effect
Hőmérsékletmérés: a termoelektromos effektus (Seebeck, 1821!)
The Seebeck effect is the conversion of temperature differences directly into electricity.
This effect was first discovered, accidentally, by the Estonian physicist Thomas Johann Seebeck in 1821, who found
that a voltage existed between two ends of a metal bar when a temperature gradient ΔT existed in the bar.
The effect is that a voltage, the thermoelectric EMF, is created in the presence of a temperature difference between
two different metals or semiconductors. This causes a continuous current to flow in the conductors if they form a
complete loop. The voltage created is of the order of several microvolts per degree difference.
SA and SB are the Seebeck coefficients (also called
thermoelectric power or thermopower) of the metals A and B,
and T1 and T2 are the temperatures of the two junctions. The
Seebeck coefficients are non-linear, and depend on the
conductors' absolute temperature, material, and molecular
structure. If the Seebeck coefficients are effectively constant
for the measured temperature range, the above formula can be
approximated as:
Fordítottja: Peltier-effektus; hűtőgép!
Sűrűségmérés
Az areométer (hydrometer) a borászatban
http://www.widdernet.de/saccharimeter.html
Saccharimeter, Brix Hydrometer
The saccharimeter measures the percentage of sugar content in
a liquid.
The most common types of saccharimeter are according to:
Brix %, Mas % at 20 C / 68 F or previously acc. to weight gew.%
Breweries used to measure in Balling.
A weight % or gew.% scale is based on 1 kilogram out of
100. In case of a measurement of 50 Wt.%, 5o kilograms are
pure sugar and the rest is water. In Brix or Mas it is the same
and even in Balling in case of 20 C / 68 F !
How to use: For using a saccharimeter you require a test jar to
make an exact and easy reading! Before and after use clean
the saccharimeter and test jar with warm water and dry before
use. The saccharimeter should also be wiped dry with a linen
cloth. After cleaning, the saccharimeter should be held only
from the thin part above the paper scale. The clean liquid is first
poured into the test jar, leaving at least 2” / 5 cm from the rim
free. Close the test jar with a clean plastic foil and with the
palm of the hand, shake 10 times! Be careful if acid or lye is in
your testing liquid ! The saccharimeter is now dipped slowly
into the liquid until it floats freely. The saccharimeter has to
be free of bubbles! Do not let the saccharimeter fall into the
test jar! The reading is taken at eye level at the spot where the
thin part or stem intersects the liquid, i.e. at the level of the
liquid surface. Record the temperature of the liquid. Take care
of the temperature of room, liquid and instrument is the same.
Store test jar, liquid, instrument about 4 hours in the same
room you test!
Sűrűségmérés Mohr-Westphal-mérleggel
Mint ismeretes, Archimedes elve alapján a folyadékok sűrűsége meghatározható azáltal, hogy
megmérjük egy üvegtest súlyveszteségét az illető folyadékban, majd 4C° hőmérsékletű vízbe mártva.
Amit a szerkezeti képlet nem fejez ki: OPTIKAI IZOMÉRIA
http://en.wikipedia.org/wiki/Chirality_(chemistry)
The term chiral is used to describe an object which is nonsuperimposable on its mirror image. In terms of chemistry,
these objects are usually molecules and the study of chiral
molecules and associated phenomena is a very active area.
A molecule is chiral when it cannot be superimposed on its
mirror image (see diagram) with the two mirror image forms
referred to as enantiomers. A mixture of equal amounts of the
two enantiomers is said to be a racemic mixture. Chirality is
of interest because of its application to stereochemistry in
inorganic chemistry, organic chemistry, physical chemistry
and biochemistry. The study of chirality falls in the domain
of stereochemistry.
The term non-superimposable distinguishes mirror images which are superposable, such as the letter "A" and its mirror image,
from those that are not. The classic example of this are human hands. The left hand is a non-superposable mirror image of the right
hand: No matter how the two hands are oriented relative to one another, one cannot line up all the major features of one hand with
the other, whereas such an operation is trivial for a non-chiral mirror image (e.g., the letter "A").
The two "hands" (enantiomers) of a chiral molecule are sometimes referred to as optical isomers.
The two enantiomers of bromochlorofluoromethane
It is the symmetry of a molecule (or any other object) that determines whether it is chiral or not. Kiemelés FG: Technically, a
molecule is achiral (not chiral) if and only if it has an axis of improper rotation; that is, an n-fold rotation
(rotation by 360°/n) followed by a reflection in the plane perpendicular to this axis which maps the molecule onto itself. (See
chirality (mathematics).) A chiral molecule is not necessarily dissymmetric (completely devoid of symmetry) as it can have, for
example, rotational symmetry. A simplified rule applies to tetrahedrally-bonded carbon, as shown in the illustration: if all four
substituents are different, the molecule is chiral.
A rule of thumb for determining the D/L isomeric form of an
amino acid is the "CORN" rule. The groups:
COOH, R, NH2 and H (where R is an unnamed carbon
chain) . are arranged around the chiral center carbon
atom. Sighting from the hydrogen atom, if these groups
are arranged counter-clockwise around the carbon atom,
then it is the D-form. If clockwise, it is the L-form.
C&EN, August 28, 2006 Volume 84, Number 35 pp. 43-45
A bűnös: tesztoszterone
Amit mérnek: két optikai izomer aránya
tesztoszterone-/epitesztoszterone
Epitestosterone, as its name suggests, is an epimer
of testosterone-a stereoisomer that differs only in
the configuration at one chiral center, which in this
case is the hydroxyl group at C-17 of the steroid
ring system.
MSU Gallery of Chemists' Photo-Portraits and Mini-Biographies
Svante August Arrhenius
1859-1927
Portrait: 3
Location - Floor: First - Zone: Room 138 - Wall: South - Sequence: 6
Source: Chemical Heritage Foundation
Sponsor: Kris A. Berglund
This Swedish physical chemist is best known for his theory of electrolytic dissociation in aqueous solution,
first presented for his doctorate thesis at the University of Uppsala when he was 24. The idea that oppositely
charged ions resulting from dissociation of molecules could be present in the same solution initially met a
hostile reception, but with support from Ostwald, van't Hoff and others the theory was gradually accepted. He is
also known for the Arrhenius Equation k = A exp -E/RT, which describes the effect of temperature on reaction
rates. He was instrumental in establishing physical chemistry as a separate discipline. A man of eclectic
scientific interests, he later published papers on immunology, cosmology and geology. He was awarded the
1903 Nobel Prize in Chemistry. http://poohbah.cem.msu.edu/Portraits/PortraitsHH_Detail.asp?HH_LName=Arrhenius
“Kettős szubsztitúciós” reakció a szerves kémiában:
2005. évi kémiai Nobel-díj
Lewis savak fontos alkalmazása: Friedel-Crafts katalizátorok, pl. AlCl3
Alkilezés
Acilezés
RCl + AlCl3  R+ (karbokation!)+ AlCl4-
Charles Friedel, born in Strasbourg on March 12, 1832,
was not only a chemist, but also a mineralogist. Friedel
studied at the Sorbonne in Paris. He died in 1899.
James Mason Crafts, born in 1839, studied chemistry first
in Germany and then in France after graduating in 1858
from Harvard. Crafts died in 1917 after spending his career
divided between the U.S. and Sorbonne.
Friedel and Crafts collaborated with one another from
1874-1891. In 1877 they discovered what is now known as
the Friedel-Crafts reaction: the alkylation karbokation or
acylation of an aromatic compound catalyzed by a Lewis
acid.
Crafts
Friedel
Friedel jegyzőkönyve
Sav-bázis elméletekhez:
Szupersavak
Oláh György, 1994-es Nobel-díj
Press Release: The 1994 Nobel Prize in Chemistry 12 October 1994
The Royal Swedish Academy of Sciences has decided
to award the 1994 Nobel Prize in Chemistry to
Professor George A. Olah, University of Southern
California, USA for his contributions to carbocation
chemistry.
http://www.psc.edu/science/2000/klein/getting_jump_on_superacids.html
superacids as chemical superheroes. These fascinating compounds have, since the 1960s,
become an essential tool of the chemical industry. Their powerful ability to react with and break
down raw petroleum brings us such products as high-strength plastics and lead-free, highoctane gas. Exotic processes like coal gasification are unthinkable without superacids.
The strongest superacid is antimony pentafluoride in hydrogen fluoride (SbF5/HF), and experiments
have shown that these solutions conduct electricity better than can be accounted for by ionic diffusion,
SbF5 - Lewis-sav; SbF5/HF szupersav; mechanizmus bizonytalan;
SbF5 + HF SbF6- + H+ nyilván fontos,
A fő kérdés az lehet, hogy a proton milyen formában van jelen?
(ionosnál jobb vezetés, HF..HF... láncon fut végig a protoncsere)
Superacids are so strong that they can protonate such extremely weak bases as the alkanes,
as was shown by Olah and independently by H. Hogeveen. Thus, pentacoordinated
carbonium ions have been obtained from methane higher alkanes and various cycloalkanes.
Methane gives the
methionium ion CH5+
Understanding the Infrared Spectrum of Bare CH5+
Oskar Asvany,1* Padma Kumar P,2* Britta Redlich,3 Ilka Hegemann,2
Stephan Schlemmer,1,4 Dominik Marx2
Science, Vol 309, Issue 5738, 1219-1222, 19 August 2005
Call movie :
ProgramFiles/ch5+_8000