New Equilibrium Resources

AUS-e-TUTE has just added new tutorials, games, tests, exams, drills and worksheet/quiz wizards.

• Equilibrium Constants
• Q vs K : Predicting Direction of Reaction
• K_w : Ion Product for Water
• K_a : Acid Dissociation Constants
• K_b : Base Dissociation Constants
• K_sp : Solubility Products
• K_P and K_c
  

Art Meets Science

Scientists have been using state-of-the-art gas-chromatography-mass-spectroscopy (GC-MS) to study the organic chemistry of old master paintings in the UK National Gallery's collection. GC-MS has been used to study the characterisation and composition of paint binding media, additions to paint media such as resins, and the composition of old varnishes.

Paint binding media include drying oils such as linseed oil, walnut oil and poppy seed oil. Analysis can show whether the oil was pre-treated by heat-bodying, or thickening, before use by the painter. Added resins can be identified and the state of degradation of the binder assessed. Paintings in other media such as egg tempera can be identified, as well as complex combinations of media.

One such painting studied was The Virgin and Child with an Angel, originally attributed to the Renaissance painter-goldsmith Francesco Francia and dated ~1490. The authenticity of the painting was queried in 1954 when another version of the same painting appeared on the market. In 2009, GC-MS was used to test the paint media and varnish, with the conclusion that the painting in the UK collection was a fake painted in the 19th century.

If you happen to be in the UK during July, you can get to see the results of this research for yourself:
http://www.nationalgallery.org.uk/about-us/press-and-media/close-examination

Now, if you happen to be in Australia, you have only a few days left to get yourself to Federation Square in Melbourne to see Rafael Lozano-Hemmer's amazing "Solar Equation" installation. This incredible piece of physics-meets-art is a simulation of the Sun, 100 million times smaller than the real thing, and compresses the entire 11 year solar cycle including solar flares and sunspots into a few short minutes of visual excitement.
http://www.fedsquare.com/index.cfm?pageID=373

Trifluoromethyl Groups in Pharmaceuticals

The trifluoromethyl group is a component of several commonly used drugs including the antidepressant Prozac, arthritis medication Celebrex, and Januvia which is used to treat the symptoms of diabetes. Trifluoromethyl groups are also a common component of agricultural chemicals such as pesticides.

Chemists often use hydrogen fluoride to attach a trifluoromethyl group to an organic compound, but under the conditions of the reaction this might produce unwanted reaction products. MIT chemists have designed a new way to attach a trifluoromethyl group to certain compounds using a palladium catalyst. The key to the success of this catalyst has been the use of a ligand called BrettPhos. During the reaction, a trifluoromethyl group is transferred from a silicon carrier to the palladium, displacing a chlorine atom. The trifluoromethyl containing molecule is then released and the catalytic cycle begins again. The chemists have tried the synthesis with a variety of aryl compounds and have achieved yields between 70% and 94%.

Reference:
Eun Jin Cho, Todd D. Senecal, Tom Kinzel, Yong Zhang, Donald A. Watson, Stephen L. Buchwald. The Palladium-Catalyzed Trifluoromethylation of Aryl Chlorides. Science, 2010; 328 (5986): 1679-1681 DOI: 10.1126/science.1190524

Study Questions

1. Write the chemical formula for the trifluoromethyl group and for hydrogen fluoride.
2. Write a chemical equation to show the possible reaction between hydrogen fluoride and cyclohexane.
3. Write a chemical reaction to show the possible reaction between hydrogen fluoride and cyclohexene.
4. For each reaction above, assuming you start with 100g of each reactant, what mass of fluorinated product would be produced if the yield was 70%?
5. For each reaction above, assuming you begin with 25 moles of each reactant, what mass of fluorinated product would be produced if the yield were 94%?
6. For the catalytic reaction discussed in the above article, why do you think the reaction does not produce a 100% yield?
   

Element 114

About 10 years ago, scientists in Dubna, Russia, reported the observation of element 114. Scientists at Berkeley, USA, and GSI Helmholtzzentrum für Schwerionenforschung in Darmstadt Germany have also reported observations of element 114.

In the most recent GSI experiment using the 120 meter long GSI particle accelerator, the scientists fired calcium ions onto a plutonium coated foil. The nuclei undergo fusion to form the nucleus of the new element. The atoms of element 114 were then separated from the other products of the reaction and identified on the basis of the radiation emitted during their decay. Two different isotopes of element 114 were identified with mass numbers 288 and 289. The measured half-lives are of the order of one second.

Russian reports on the creation of elements up to atomic number 118 are yet to be confirmed.

Reference:
Helmholtz Association of German Research Centres (2010, June 22). Chemical element 114: One of heaviest elements created. ScienceDaily. Retrieved June 23, 2010, from http://www.sciencedaily.com­ /releases/2010/06/100622102347.htm

Study Questions

1. What is the atomic number of the element 114?
2. What are the atomic numbers of calcium and plutonium?
3. Define the term atomic number.
4. Write an equation to represent the fusion of calcium and plutonium.
5. What is meant by the term isotope?
6. For each of the isotopes of element 114 in the article above, give the atomic number, mass number, number of protons, number of neutrons, and number of electrons in an atom of each isotope.
7. Write a nuclear equation for the decay of each isotope of element 114 assuming it undergoes beta decay.
8. Write a nuclear decay equation for the decay of each isotope of element 114 assuming it undergoes alpha decay.
9. What is meant by the term half life?
   
10. If the half-life an isotope of element 114 is assumed to be 1 second, what percentage of the original isotope will be present after 10 seconds?
    

Brownian Motion Machine

In 1912, Marian Smoluchowski proposed a prototype for an engine at the molecular scale which he thought could convert Brownian motion into work. It consisted of a series of vanes mounted on an axis and set into motion by molecular bombardment. An asymmetrical cog ensuring that the axis could only rotate in one direction so that the device could perform work such as lifting a weight.

In 1963, Richard Feynman demonstrated that the second law of thermodynamics would prevent the device from working in a system that was in a state of thermal equilibrium.

Scientists from the University of Twente, the University of Patras in Greece and the Foundation for Fundamental Research on Matter (FOM) have now demonstrated the first working Brownian Motion engine. Using a granular gas, a solid suspended in air that is constantly vibrated, a constant supply of energy is required to maintain the granular gaseous state so that the system is never at thermal equilibrium. Once the vanes of the engine start rotating, they induce a rotating motion in the gas known as a convection roll, which reinforces the movement of the device and allows for virtually continuous rotation.

Reference:
Peter Eshuis, Ko van der Weele, Detlef Lohse and Devaraj van der Meer. Experimental Realization of a Rotational Ratchet in a Granular Gas. Phys. Rev. Lett., 104, 248001 (2010) DOI: 10.1103/PhysRevLett.104.248001

Study Questions:

1. What is brownian motion?
2. What are the three laws of thermodynamics?
3. What is meant by term thermal equilibrium?
   
4. Why would the second law of thermodynamics prevent this device from working in a system that was at thermal equilibrium?
5. List the ways in which a granular gas is similar to compound in the gaseous state.
6. List the ways in which a granular gas is different to a compound in the gaseous state.
   

Fluorescence and Counterfieting

Fluorescence is an emission of electromagnetic radiation. Certain organic dyes are fluorescent, when hit within a certain wavelength range they emit light at a greater wavelength. The wavelength and intensity of this light depends on the physical and chemical properties of the materials to which the dye was applied.

To make a product counterfeit-proof, multiple dyes can be added to the material in very minute quantities, such as just a few parts per billion, to create a marker. At such low concentrations, the marker is virtually impossible to decode, and the counterfeit protection cannot be removed since it permeates the whole material. Fluorescent dye markers produce precise characteristics so it is easy to recognize if the material is original or if it is a copy.

Reference:
Fraunhofer-Gesellschaft (2010, June 15). Brilliant counterfeit protection. ScienceDaily. Retrieved June 18, 2010, from http://www.sciencedaily.com­ /releases/2010/06/100614093627.htm

Study Questions

1. What is meant by the term electromagnetic radiation?
2. Fluorescein is an example of a fluorescent dye that has been used as a marker for airplanes downed at sea. Find the structural formula for fluorescein.
3. Some fluorescent compounds are used as fabric whiteners in washing powders and are referred to as optical bleaches. Find an example of an optical bleach and describe how it works.
   
4. A number of naturally occurring minerals are fluorescent. Can you list examples of these?
5. Phosphorescence is similar to fluorescence. What is the difference between phosphorescence and fluorescence?
6. If an aqueous solution of fluorescein has a concentration of 175ppb, what is its equivalent concentration in,

• ppm
• parts per hundred
• g/mL
• μg/mL
• mol/L
  

Hard Metal

Hard metal is a mixture of a hard carbide phase, tungsten carbide, and a tougher metal phase, cobalt. It is produced by sintering, a process in which fine powders of tungsten carbide and cobalt are heated up so that the cobalt melts and the material is pulled together by capillary force. This results in a solid material consisting of hard tungsten carbide grains surrounded by the tougher cobalt-rich cement phase.

The size of the tungsten carbide grains determines the hardness of the hard metal.
Scientists know that by doping the material, that is, by adding another substance in tiny amounts, they can limit the size of the grains. For example, adding a tiny amount of vanadium can limit the growth of the grains, instead of growing grains 1/1000 mm in diameter, the addition of vanadium results in grain sizes about 1/10,000 mm. Scientists at the Chalmers University of Technology in Sweden have just used high-resolution electron microscopy to observe an extremely thin layer, only 2 atom layers thick, of a cubical structure on the tungsten carbide grains which they believe is affecting the growth of the grains.

Reference:
Expertanswer (2010, June 14). Materials researchers micromanage atoms in hard metal. ScienceDaily. Retrieved June 16, 2010, from http://www.sciencedaily.com­ /releases/2010/06/100614093343.htm

Study Questions:

1. Write the symbol for each of the following elements: tungsten, carbon, cobalt, vanadium.
2. To which group of the Periodic Table do tungsten, cobalt and vanadium belong?
3. Give possible oxidation states (numbers) for tungsten, cobalt, vanadium and carbon.
   
4. Suggest a formula for tungsten carbide.
5. Would you expect larger or smaller grains of tungsten carbide to grow at higher temperatures?
   

Life on Mars?

Was there life on Mars?
Scientists continue to look for organic compounds such as proteins in Martian soil, but to date none have been found, even though organic molecules are found in many other places in the Solar System.

Astrobiologists are beginning to wonder if the iron oxides that make up the soil on Mars, giving the planet its distinctive red colour, are photocatalysts which use energy from ultraviolet light to oxidize carbon-containing molecules trapped in soil particles converting them to carbon dioxide and gases such as methane. This suggests that the absence of proteins or other organic molecules on Mars does not necessarily mean it has never supported life forms.

Reference:
Ilya A. Shkrob, Sergey D. Chemerisov, Timothy W. Marin. Photocatalytic Decomposition of Carboxylated Molecules on Light-Exposed Martian Regolith and Its Relation to Methane Production on Mars. Astrobiology, 2010; 10 (4): 425 DOI:
10.1089/ast.2009.0433

Study Questions:

1. Define an organic compound.
2. What elements are proteins made up of?
3. Proteins are produced when what smaller compounds react?
4. What is the name given to the bond between these smaller compounds making up a protein?
5. Why do you think Astrobiologists look for proteins in order to determine if life existed on Mars in the past?

Further Reading:

1. http://www.ausetute.com.au/proteins.html
2. http://www.ausetute.com.au/aminoacid.html
   

Structure of Vodka

Vodka is a colourless, tasteless solution sold as an 80-proof beverage, which means it is a solution of 40% ethanol (ethyl alcohol) and 60% water. There are many different brands of Vodka at different prices, and people claim to be able to "taste" the difference. Scientists at the University of Cincinnati and the Moscow State University have been studying this phenomenon.

Dmitri Mendeleev, a Russian Chemist famous for his work on the Periodic Table, believed that a solution of 40% ethanol and 60% water would form peculiar clusters of molecules called hydrates.

Linus Pauling, a Nobel Prize winning Chemist, thought the hydrate clusters might consist of an ethanol molecule surrounded by a framework of hydrogen-bonded water molecules.

The scientists from the the Universities of Cincinnati and Moscow State analyzed the composition of 5 popular Vodka brands and found that they differed in their concentrations of ethanol hydrates. When people express a preference for one Vodka brand over another, it is not a question of "tasting" different, they appear to be perceiving the internal structure of the Vodka. Vodkas with a low concentration of ethanol hydrates might be perceived by drinkers as watery.

Reference:
Naiping Hu, Dan Wu, Kelly Cross, Sergey Burikov, Tatiana Dolenko, Svetlana Patsaeva, Dale W. Schaefer. Structurability: A Collective Measure of the Structural Differences in Vodkas. Journal of Agricultural and Food Chemistry, 2010; DOI: 10.1021/jf100609c

Study Questions:

• The concentration of beverages containing ethanol, such as spirits, are often labelled as "proof", eg, 100 proof, 80 proof. What other ways are there to express the concentration of solutions?

• Convert 80 proof to its equivalent for each of the different concentration measures you listed above.

• For the ethanol molecule, write

1. the structural formala
2. the condensed structural formula
3. molecular formula
4. empirical formula

• What is hydrogen bonding?
• Draw a diagram showing how water molecules can hydrogen bond to each other.
  

• Draw a diagram to represent an ethanol molecule surrounded by 5 hydrogen-bonded water molecules.
• At high alcohol concentration, clusters of ethanol molecules appear. What could hold these ethanol molecules together in a cage-like structure?
  

New Membrane for Desalination

Reverse-osmosis desalination uses high pressure to force polluted water through the pores of a membrane. Water molecules pass through the pores of the membrane, but mineral salt ions, bacteria and other impurities do not. Over time, the pores become clogged and the membrane damaged, requiring expensive cleanup and membrane replacement.

UCLA scientists have produced a new membrane which could increase membrane life and reduce desalination plant operational costs. The new membrane is synthesized in a three step process:

1. synthesis of a polyamide thin-film composite
2. activation of the polyamide surface with atmospheric pressure plasma to create active sites on the surface
3. initiation of a graft polymerization reaction on the activation sites using a monomer solution to create a polymer "brush layer"

The polymer chains of the brush layer, which are chemically anchored to the polyamide surface, are in constant motion, much like seaweed that is in constant motion but anchored to the sea floor. This motion makes it difficult for bacteria and other colloidal matter to anchor to the surface of the membrane increasing the life expectancy of the membrane.

References:

1. Nancy H. Lin, Myung-man Kim, Gregory T. Lewis, Yoram Cohen. Polymer surface nano-structuring of reverse osmosis membranes for fouling resistance and improved flux performance. Journal of Materials Chemistry, 2010; DOI: 10.1039/b926918e
2. Myung-man Kim, Nancy H. Lin, Gregory T. Lewis, Yoram Cohen. Surface nano-structuring of reverse osmosis membranes via atmospheric pressure plasma-induced graft polymerization for reduction of mineral scaling propensity. Journal of Membrane Science, 2010; DOI: 10.1016/j.memsci.2010.02.053

Study Questions:

1. What is osmosis?
2. Name some mineral salt ions you would expect to find in seawater.
3. What is a monomer?
4. What is a polymer?
5. What is meant by the term polymerization?
6. Describe a polyamide.
7. Draw a table listing some polymers, their respective monomers, and the properties and uses of the polymers
   

Heavy Fermions

Scientists are interested in studying heavy fermion behaviour because it could lead to the design of new materials for high temperature super-conductors.

Cornell University Scientists imaging the electronic properties of a material composed of uranium, ruthenium and silicon, have found that the effects of heavy fermions begin to appear as the material is cooled below 55K, and, an even more unusual electronic phase transition occurs below 17.5K.

This phase transition was studied using spectroscopic imaging scanning tunneling microscopy (SI-STM) which measures the wavelength of electrons on the surface of the material in relation to their energy. From the wavelength and energy measurements scientists calculated the effective electron mass and found that these electrons were either very heavy, or, that they were acting like very heavy electrons because they were being slowed down. This suggests that these electrons are interacting with the uranium atoms, that is, acting as particles rather than acting as a wave.

Reference:
A. R. Schmidt, M. H. Hamidian, P. Wahl, F. Meier, A. V. Balatsky, J. D. Garrett, T. J. Williams, G. M. Luke & J. C. Davis. Imaging the Fano lattice to 'hidden order' transition in URu₂Si₂. Nature, 2010; DOI: 10.1038/nature09073

Study Questions

1/ What is a fermion?

2/ What is a super-conductor?

3/ What could high temperature superconductors be used for?

4/ What is the atomic symbol for:

• uranium
• ruthenium
• silicon

5/ To which group of the Periodic Table do each of the following elements belong?

• uranium
• ruthenium
• silicon

6/ Convert the following temperatures in Kelvin to ^oC.

• 55K
• 17.5K

7/ What is the relationship between mass, energy and wavelength that would allow Scientists to calculate the effective mass of an electron?

8/ Why would electrons appear to be heavier if they are slowed down?

Sticky Mortar?

1,500 years ago, Chinese construction workers developed what was probably the world's first composite mortar, a mortar made from both organic and inorganic materials. The mortar was made by combining sticky rice soup with slaked lime, limestone which has been heated to high temperatures then exposed to water. This "sticky rice" mortar was stronger and more resistant than pure lime mortar.

Scientists have recently discovered that amylopectin, a type of polysaccharide, is the ingredient in the sticky rice that is responsible for the strength of this ancient mortar. The amylopectin in the mortar acts as inhibitor, controlling the growth of the calcium carbonate crystals, resulting in a compact microstructure which leads to greater mechanical strength.

Reference:
Fuwei Yang, Bingjian Zhang, Qinglin Ma. Study of Sticky Rice-Lime Mortar Technology for the Restoration of Historical Masonry Construction. Accounts of Chemical Research, 2010; : 100510131945076 DOI: 10.1021/ar9001944

Galvanizing AUS-e-NEWS

Ever wondered what galvanizing really is?
What is the chemistry behind the process?

The June 2010 issue of AUS-e-NEWS, AUS-e-TUTE's newsletter, takes a look at galvanizing.

AUS-e-NEWS has now been emailed out to all members and subscribers.
If you have not received your copy, or, if you would like to be added to our list of subscribers, please contact us.