2012 Chemistry Calendar

The quintessential 2012 chemistry calendar is now available for download from ausetute.com.au

Now there's no excuse for forgetting to celebrate the birthday of some celebrated chemists !

Flerovium and Livermorium?

Elements 114 and 116 are the latest additions to the Periodic Table of the elements,
created by smashing calcium ions into a curium target to create element 116. Element 116 decayed almost immediately into element 114. The scientists also created element 114 separately by replacing curium with a plutonium target.
Both elements were first produced at the Joint Institute for Nuclear Reasearch, Dubna, Russia, and Lawrence Livermore chemists. Element 114 was first produced in 1998 and element 116 in 2000. The proposed name for element 114 is flerovium with the symbol Fl, and, the proposed name for element 116 is livermorium with the symbol Lv.

Flerovium was chosen to honour the Flerov Laboratory of Nuclear Reactions where element 114 was synthesized. The laboratory itself is named after Georgiy N. Flerov (1913-1990) , a renowned physicist who discovered the spontaneous fission of uranium and was a pioneer in heavy-ion physics. He is the founder of the Joint Institute for Nuclear Research.

Livermorium was chosen to honour Lawrence Livermore National Laboratory (LLNL) and the city of Livermore, California. A group of researchers from the Laboratory, along with scientists at the Flerov Laboratory of Nuclear Reactions, participated in the work carried out in Dubna on the synthesis of superheavy elements, including element 116. The element lawrencium, element 103, was named after LLNL's founder E.O. Lawrence.

The new names were submitted to the IUPAC in October 2011 and now remain in the public domain. The new names will not be official until about March 2012 when the public comment period is over.

Reference
DOE/Lawrence Livermore National Laboratory (2011, December 1). Scientists propose new names for elements 114 and 116. ScienceDaily. Retrieved December 11, 2011, from http://www.sciencedaily.com­ /releases/2011/12/111201125400.htm

Further Reading
History of the Elements
Periodic Table of the Elements
Isotopes
Nuclear Decay

Suggested Study Questions

1. What is the atomic number of each of the following elements?
   
   • calcium
   • curium
   • plutonium
   • uranium
   • lawrencium
     
   • flerovium
   • livermorium
2. How many protons are in the nucleus of an atom of each of the following elements?
   
   • calcium
   • curium
   • plutonium
   • uranium
   • lawrencium
     
   • flerovium
   • livermorium
3. Calculate the number of electrons present in an atom of each of the following elements:
   
   • calcium
   • curium
   • plutonium
   • uranium
   • lawrencium
     
   • flerovium
   • livermorium
4. For each of the elements above, state whether it is found in nature or whether it is man-made.
   
5. Assuming each of the elements above forms an ion with a charge of +2 then
   • how many electrons will be present in each ion?
   • how many protons will be present in each ion?

6. Write a possible nuclear equation to show the production of livermorium from calcium ions and curium atoms.

7. Write a possible nuclear equation to show the production of flerovium from plutonium atoms and calcium atoms.

8. Write a possible nuclear decay equation to show how livermorium could decay to produce flerovium.

9. The suggested symbol for Flerovium is Fl. List all other elements that have a symbol which includes the letter F.

10. The suggested symbol for Livermorium is Lv. List all the other elements that have a symbol which includes the letter L.
    

    
    

Liquid Chlorine?

What is wrong with this picture?

Is it possible for an ordinary plastic bottle with a screw cap to contain liquid chlorine?
Probably not!

Chlorine exists as a diatomic yellow-green gas at room temperature and pressure, that is, chlorine exists as Cl_2(g).
In order to produce liquid chlorine we could:

• lower the temperature of the bottle to change the gas into a liquid at atmospheric pressure.
• raise the pressure within the bottle to change the gas into a liquid at room temperature.
• lower the temperature and raise the pressure at the same time.
  

At 1 atmosphere pressure, the melting point of chlorine is about -101^oC and its boiling point is about -34^oC. So, chlorine will be a liquid at temperatures between -34^oC and -101^oC.
For comparison, your refrigerator is probably set to maintain a temperature of about 4^oC while the freezer has a temperature of around 0^oC, not cold enough to liquefy chlorine! A plastic bottle sitting on the shelf in your garage is not going to be cold enough to store chlorine as a liquid!

Gaseous chlorine could also be changed into a liquid by applying pressure. At room temperature this can be achieved with a pressure about 8 times that of atmospheric pressure, which is highly unlikely to occur in our plastic bottle with the screw cap.

So, the fluid in the plastic bottle labelled "liquid chlorine" is not chlorine. What is it?
It is most likely to be an aqueous solution of sodium hypochlorite, NaClO_(aq).
Aqueous solutions of sodium hypochlorite are produced by bubbling chlorine gas, Cl_2(g), through an aqueous solution of sodium hydroxide, NaOH_(aq) at room tmeperature:
Cl_2(g) + 2NaOH_(aq) → NaClO_(aq) + NaCl_(aq) + H₂O_(l)
When the aqueous sodium hypochlorite solution is mixed with dilute acid, chlorine gas is released:
2H⁺_(aq) + OCl^-_(aq) + Cl^-_(aq) → Cl_2(g) + H₂O_(l)

The chlorine gas that is released can kill bacteria and other microbes, so aqueous solutions of hypochlorites are often used as disinfectants.

Further Reading
Chemical and Physical Changes
Kinetic Theory of Gases

Suggested Study Questions:

1. Identify each of the changes below as either a chemical change or a physical change:
   • freezing water in a freezer
   • boiling water in a kettle
   • cooling chlorine gas to make chlorine liquid
   • boiling liquid chlorine to make chlorine gas
   • bubbling liquid chlorine though aqueous sodium hydroxide solution to form a solution of sodium hypochlorite
     
   • bubbling chlorine gas through water to make hypochlorous acid
2. Name each of the physical changes above.
3. Use the kinetic theory of matter to explain what happens to chlorine molecules when:
   • chlorine gas is cooled to produce liquid chlorine at 1 atm pressure
     
   • chlorine gas is subjected to a pressure of more than 8 atmospheres at 25^oC
   • chlorine gas is cooled to 4^oC
4. Sodium hydroxide has a melting point of 319^oC and a boiling point of 1390^oC at 1 atm pressure. Describe how you could produce sodium hydroxide liquid.
5. Which of the following pure substances could be kept in an ordinary plastic bottle with a screw cap on a shelf in your garage?
   
   • ozone (melting point -192^oC, boiling point -110⁰C)
   • potassium chloride (melting point 772^oC, boiling point 1407^oC)
   • sulfur dioxide (melting point -75^oC, boiling point -10^oC)
   • ethanol (melting point -114^oC, boiling point 78^oC)
     
   
   
   

World's Lightest Material?

UC Irvine, HRL Laboratories and the California Institute of Technology have announced that they have succeeded in making the world's lightest material, with a density of 0.9 mg/cm³.

This material is made up of a metallic lattice of interconnected hollow tubes with walls a thousand times thinner than a human hair. Because of this open lattice structure, the material is actually made up mostly of air, 99.99% air .

But what is the metal making up this new material?

We know the density of the new material, so we can calculate the mass of a 1cm cubed volume of this material:

1cm³ of the new material would have a mass of 0.9 mg = 0.0009g.

If 99.99% of the mass of this material is made up of air, then

the mass of air = 99.99/100 x 0.0009 = 8.991 x 10^-4g (0.8991 mg)

and the mass of metal in the new material = 0.0009 - 8.991 x 10^-4 = 9 x 10^-7g (9 x 10^-4 mg)

If we assume that 0.00001% of the volume of the new material is metal, then

the volume of metal = 0.00001/100 x 1cm³ = 1 x 10^-7cm³

So, the density of the pure metallic solid would be 9 x 10^-7g/10^-7cm³ = 9g/cm³

If we compare this calculated density of the metal to a list of common metals as shown below,

Pure Substance	State	Density (g/cm3) at 25oC and 1atm
gold	solid	19.3
mercury	liquid	13.6
lead	solid	11.4
silver	solid	10.5
copper tin	solid solid	9.0 7.3
zinc	solid	7.1
aluminium	solid	2.7

then we see it is possible that the new material is made up of copper.

Reference

T. A. Schaedler, A. J. Jacobsen, A. Torrents, A. E. Sorensen, J. Lian, J. R. Greer, L. Valdevit, W. B. Carter.Ultralight Metallic Microlattices. Science, 2011; 334 (6058): 962 DOI: 10.1126/science.1211649

Further Reading

Density Calculations

Suggested Study Questions

1. Using the table of densities above, calculate the mass in grams of a
   • cubic centimetre of gold
   • a cubic metre of copper
   • a cubic millimetre of silver
   • a cubic kilometre of zinc
2. Using the table of densities above, calculate the volume in cubic centimetres of
   • 1g of copper
   • 100mg of lead
   • 4500μg of aluminium
   • 2kg of silver
3. Brass is a mixture of copper and zinc. A sample of brass has a density of 8.5g/cm³
• What is the mass a cubic centimetre volume of this brass sample?
• If the sample were made up of equal masses of copper and zinc, what is the mass of copper in the sample?
4. A sample of brass was produced using 500cm³ of each of copper and zinc.
• What mass of copper is present in the brass?
• What mass of zinc is present in the alloy?
• Assuming additivity of volumes, what is the density of this brass sample?
5. Cymbals are commonly made of bronze which is a mixture of about 10% (by mass) tin and 90% (by mass) copper. For a 100g sample of bronze, calculate
• the mass of copper present in the sample
• the volume of copper this mass represents
• the mass of tin present in the sample
• the volume of tin this mass represents
• the density of the bronze sample assuming additivity of volumes
6. Typically, bronze contains copper and about 12% (by mass) tin. Calculate the density of a sample of this bronze.
7. Bronze coins often contain copper and about 5% tin. Calculate the density of the bronze used to make coins.
8. The brass used to make springs and screws is often 65% (by mass) copper and 35% (by mass) zinc. Calculate the density of the alloy in a brass screw.

Newest AUS-e-TUTE Resources

New AUS-e-TUTE Resources for All Members:

Electrolyisis of Molten Salts Tutorial : http://www.ausetute.com.au/elymsalt.html

Electrolyisis of Molten Salts Game

Electrolyisis of Molten Salts Test

Electrolyisis of Molten Salts Game

Electrolyisis of Aqueous Salt Solutions Tutorial : http://www.ausetute.com.au/elyqsalt.html

Electrolyisis of Aqueous Salt Solutions Game

Electrolyisis of Aqueous Salt Solutions Test

Electrolyisis of Aqueous Salt Solutions Exam

New AUS-e-TUTE Resources for Teachers:

Learning Activities (now listed under tutorials in the Teachers Only section of the website):

-Electrolysis of Molten Salts

-Electrolysis of Aqueous Salt Solutions

-Periodic Table Trends : Atomic Radius

-Periodic Table Trends : First Ionization Energy

-Periodic Table Trends : Group 1

Stimulus Resources:

-Defining Electronegativity http://auseblog.blogspot.com/2011/10/defining-electronegativity.html

-Oxygen Evolution Reactions http://auseblog.blogspot.com/2011/10/oxygen-evolution-reactions.html

Oxygen Evolution Reactions

Oxygen Evolution Reactions (OER) produce molecular oxygen via chemical reactions. These reactions are being studied because of their importance to the development of energy-storage systems.

During photosynthesis, molecular oxygen is produced from water as shown in the equation below:
2H₂O → 4e + 4H⁺ + O_2(g)so photosynthesis is an Oxygen Evolution Reaction.

The electrolysis of water, is another Oxygen Evolution Reaction. Oxygen gas is produced according to the equation shown below:
2H₂O_(l) → O_2(g) + 2H_2(g)
In either case, the chemical reaction to split water in order to produce oxygen gas is not spontaneous, it requires the addition of energy. In the case of the electrolysis of water in the laboratory, electrical energy is supplied from a battery or a power pack. In the case of photosynthesis, sunlight provides the energy for the reaction in the form of photons.
A catalyst can be used to speed up the reaction. In the case of photosynthesis, chlorophyll is the catalyst present in green plants. Scientists are continually working to find a good catalyst that will work just like chlorophyll. TiO₂, SrTiO₃, and BaTiO₃ have all been investigated as possible catalysts.

A team of MIT researchers have just found one of the most effective catalysts ever discovered for an Oxygen Evolution Reaction. The new catalyst is composed of cobalt, iron, oxygen and some other metals.

Reference
J. Suntivich, K. J. May, H. A. Gasteiger, J. B. Goodenough, Y. Shao-Horn. A Perovskite Oxide Optimized for Oxygen Evolution Catalysis from Molecular Orbital Principles. Science, 2011; DOI: 10.1126/science.1212858

Further Reading
Carbon Cycle
Electrolysis
Mass-Mole Calculations
Mole Calculations
Gas Tests

Suggested Study Questions

1. Assuming 18g of water is to be split to provide oxygen gas. Calculate the maximum mass of oxygen gas that could be obtained.
2. Assuming 1L of water is to be electrolyzed at 25^oC and 1 atmosphere pressure. What is the maximum volume of oxygen gas that could be produced?
3. During the electrolysis of water, what is produced at the
   • cathode
   • anode
4. During the electrolysis of water, what is the charge on the
   • cathode
   • anode
5. During electrolysis name the electrode at which each of the processes below occurs:
   • oxidation
   • reduction
6. Write balanced equations to represent the reaction that occurs at the
   • cathode
   • anode
7. Calculate the minimum voltage that would be required in order for the electrolysis of water to produce both hydrogen gas and oxygen gas.
8. Describe a test that you could conduct in the laboratory that would allow you to say which of the gases evolved during the electrolysis of water is oxygen and which is hydrogen.
   
   
   
   
   

Defining Electronegativity

Electronegativity is defined as the power of an atom to attract electrons to itself, but it cannot be directly measured so it must be calculated using other properties of atoms. There are many different ways of calculating electronegativity.

Pauling Electronegativity
In 1932 Pauling proposed the concept of electronegativity to explain why the covalent bond formed between two different atoms, eg A-B bond, is stronger than you might expect if you were to take an average of the A-A and B-B bond strengths. Since Pauling's electronegativities are based on the differences in bond strengths between atoms, it is necessary to choose an arbitrary reference point so that these electronegativities can be compared and used to make predictions. Hydrogen, with an electronegativity of 2.20, has been used as the reference to build up a table of electronegativities. Pauling electronegativities have no units.

Mulliken Electronegativity
Mulliken electronegativities are based on the mean of the first ionization energy and the electron affinity and has the units kJ/mol or eV.

Allred-Rochow Electronegativity
Allred-Rochow electronegativity is related to the charge experienced by an electron on the 'surface' of an atom and is calculated using the ratio of effective nuclear charge experienced by the valence electrons and the square of the covalent radius.

Sanderson Electronegativity
Similar to the Allred-Rochow electronegativity, Sanderson's calculations use atomic volume instead of the square of the covalent radius.

Allen Electronegativity
Allen electronegativity is related to the average energy of the valence electrons in a free atom.

Solid State Energy Scale
In 2011, Oregon State University scientists created a new method to describe electronegativity. In this approach, electronegativity is characterised as the solid state energy of elements in a compound, and shows that electrons simply move from a higher energy to a lower energy.

Reference
Brian D. Pelatt, Ram Ravichandran, John F. Wager, Douglas A. Keszler. Atomic Solid State Energy Scale. Journal of the American Chemical Society, 2011; : 111003131629001 DOI: 10.1021/ja204670s

Further Reading
Electronegativity Trends
Electronegativity and Bond Polarity
Interactive Periodic Table of the Elements
Ionization Energy and Electron Configuration

Suggested Study Questions

1. Use the Interactive Periodic Table to find the Pauling Electronegativity for each of the following elements:
   • sodium
   • potassium
   • magnesium
     
   • calcium
   • oxygen
   • sulfur
   • chlorine
   • fluorine
2. Use the values for the electronegativities above to describe each of the following compounds as ionic or covalent:
   • sodium chloride
   • magnesium oxide
   • potassium fluoride
   • calcium oxide
   • sulfur dioxide
   • chlorine dioxide
   • ozone
3. For each of the covalent compounds above, describe the compound as non-polar or polar covalent.
4. What is meant by the term ionization energy?
5. What is meant by the term electron affinity?
6. How is electronegativity differen to electron affinity?
7. If an element has a very low first ionization energy, do you expect it to have a high of low Pauling electronegativity? Explain your answer.
8. If an element has a high Pauling electronegativity, do you expect it to have a high or low value for its electron affinity? Explain your answer.
   
   

Sunken Silver

In 1941, the British cargo ship SS Gairsoppa was carrying 7,000 tonnes of cargo from Calcutta. The cargo included pig iron, tea and about 200 tonnes of silver. A German U-boat torpedo sunk the SS Gairsoppa as it made its way to Ireland in stormy weather. While only one person out of the 85 crew members on board survived the attack, it is believed its cargo of silver is still at the bottom of the ocean.

Silver is unique because it has the highest electrical and thermal conductivity of any known element. It is a soft metal, just a little harder than gold, and is extremely ductile and malleable meaning it can be bent or beaten into almost any shape.
There were many uses for silver during World War II :

• many electrical connectors and switches were silver plated
• silver bus bars were needed for the new aluminum plants (aluminium aircraft)
• silver replaced large amounts of tin in solder
• silver was used in the reflectors in lights

There are a number of silver alloys:

• Fine silver contains 99.9% by mass silver
• Britannia silver contains 95.84% by mass silver with copper making up the remaining mass
  
• Sterling silver contains 92.5% by mass silver and 7.5% by mass copper.
• Argentium sterling silver is a modern alloy containing 92.5% silver and 7.5% by mass of copper and germanium
• Electrum is a natually occurring alloy of gold and silver. The % by mass of gold can be within the range of 70-90%.

And, silver is present in most coloured carat gold alloys:

• 9 carat gold contains 62.5% silver and 37.5% gold
• 22 carat gold contains 91.7% gold with the remaining mass made up of silver and/or copper
  

Silver is stable in pure air and water, but tarnishes when exposed to air or water containing ozone or hydrogen sulfide. In the presence of oxygen gas and hydrogen sulfide gas, elemental silver forms the dark-coloured silver (I) sulfide and water.

Reference
Shipwreck of SS Gairsoppa reveals £150m silver haul
BBC News Online
http://www.bbc.co.uk/news/uk-15061868

Further Reading
Properties of Metals and Non-metals
Percent by Mass
Writing Ionic Formula
Balancing Chemical Equations

Suggested Study Questions

1. For the element silver, give the
   • chemical symbol
   • atomic number (Z)
   • atomic mass
     
2. For each of the uses given for silver in the article above, explain which physical and/or chemical properties of silver make it ideal for that use.
3. Using the composition of the various silver alloys provided in the article above, place the alloys in order of increasing mass of silver present in a 1kg sample.
4. Using the information contained in the article above, describe the relationship between the mass of gold in a sample and the use of the term carat.
5. Place the following terms in order of decreasing mass of gold: 9 carat gold, 18 carat gold, 22 carat gold and 24 carat gold.
6. Write a word equation to describe the process of tarnishing in air that contains some hydrogen sulfide.
7. Write a balanced chemical equation for the tarnishing of silver in air that contains some hydrogen sulfide.
8. It is thought that the silver being carried by the SS Gairsoppa contained some gold. Which alloy of silver could this be? Explain your answer.
9. The SS Gairsoppa is resting 4,700m below the ocean's surface. Do you expect the silver to be tarnished? Explain your answer.
   

Skutterudites and Thermoelectric Generators

More than 60 percent of the energy produced by cars, machines, and industry around the world is lost as waste heat. If we could use this wasted energy we could improve the efficiency with which we use fuels, and benefit the environment.

Thermoelectric generators are devices which convert heat energy directly into electrical energy. Semi-conducting bismuth telluride, Bi₂Te₃, can be used to convert heat into electrical energy, but it is only about 5% efficient, too low to be useful in practical thermoelectric generators.
A number of scientists have been working with skutterudites to see if they can be used to increase the efficiency of thermoelectric generators.
Skutterudites have the general formula MX₃ in which M can be cobalt, rhodium or iridium, and X can be phosphorus, arsenic or antimony. The most promising of these compounds have been the CoSb₃. These compounds have 32 atoms in the unit cell and can be represented with the Co atoms occupying the corners of cubes.
The thermal conductivity of CoSb3 is too high for them to be used effectively.

So scientists have tried adding fillers to the structure to reduce the thermal conductivity. Rare earth elements and alkaline earth metals have been used as fillers.

Until recently these compounds have taken many days to make and have been expensive to produce. Oregan State University scientists have found a way to use microwaves to turn powdered metals into skutterudites in a few minutes and at a much lower cost. The first compound they produced using this technique was an indium cobalt antimonite compound in which indium is the filler.

Reference
Krishnendu Biswas, Sean Muir, M. A. Subramanian. Rapid Microwave Synthesis of Indium Filled Skutterudites: An energy efficient route to high performance thermoelectric materials. Materials Research Bulletin, 2011; DOI: 10.1016/j.materresbull.2011.08.058

Further Reading
Periodic Table
Writing Ionic Formula
Naming Ionic Compounds

Suggested Study Questions

1. Complete the following sentences:
   • A thermoelectric generator converts heat energy into ? energy.
   • A battery converts ? energy into electrical energy.
   • In a torch, the ? energy in the battery is converted into ? energy when the torch is turned on.
     
   • The ? energy in petrol (gasoline) is converted into ? energy when the fuel is combusted.
   • The ? energy released during combustion of a fuel can be converted into ? energy to move a car forward.
2. Skutterudites have the general formula MX₃. Write the formula of the skutterudite formed in each of the following situations:
   • M = cobalt and X = antimony
   • M = rhodium and X = phosphorus
   • M = iridium and X = arsenic
3. Give the name for each of the compounds formed in question 2.
4. For each of the following pairs of atoms, determine which is the most electronegative:
   • cobalt and antimony
   • rhodium and phosphorus
   • iridium and arsenic
5. Locate the elements cobalt, rhodium and iridium in the Periodic Table. In what ways do you expect these elements to be similar? Explain your answer.
6. Locate the elements phosphorus, arsenic and antimony in the Periodic Table. In what ways do you expect these elements to be similar? Explain your answer.
7. Give the names and chemical symbols of four examples of rare earth elements.
8. Give the names and chemical symbols of four examples of alkaline earth metals.
9. Write a possible formula for the skutterudite indium cobalt antimonite.
10. One structure has been represented as In_xCe_yCo₄Sb₁₂. Explain why this is an example of a skutterudite.
    
    
    
    

Measuring Iodine in Water

The recommended daily intake of iodine for a typical adult is about 150μg per day, of which the thyroid gland uses about half. Iodine deficiency results in a condition known as hypothyroidism which produces symptoms such as extreme fatigue, goitre, mental slowing, depression, weight gain, and low basal body temperatures. Excess iodine intake results in symptoms similar to those of iodine deficiency.
Iodine is a known disinfectant and is used to inhibit the growth of microorganisms in the drinking water stored at the International Space Station. Scientists at Iowa State University have developed a simple test to measure the concentration of iodine in this drinking water.

A 10-milliliter water sample is run through a thin, one-centimeter disk that changes colour from white to yellow to orange to rust-red as the concentration of iodine increases. A handheld device, a diffuse reflectance spectrometer, can read the disk's color changes and precisely measure the concentration of molecular iodine, or I₂. The whole process is called colorimetric solid phase extraction.

After a series of successful space tests in 2009 and 2010, this water-testing equipment is now certified operational hardware and is part of the space station's environmental monitoring toolbox.

Reference:
Iowa State University (2011, September 15). Chemists help astronauts make sure their drinking water is clean. ScienceDaily. Retrieved September 20, 2011, from http://www.sciencedaily.com­ /releases/2011/09/110914171753.htm

Further Reading
Mass Conversions
Mole Definitions
Molarity
w/v %
ppm

Suggested Study Questions

1. Convert 150μg to a mass in
   • grams
   • milligrams
   • kilograms
   • nanograms
2. Convert 10 milliliters to a volume in
   • liters
   • microliters
   • nanoliters
   • kiloliters
     
   
   
3. For 150μg of iodine, find the
   
   • moles of molecular iodine
   • moles of iodine atoms
   • number of iodine atoms
   • number of molecules of molecular iodine
     
   
   
4. In the Space Station the iodine is dissolved in the water supply. If an astronaut must consume 3L of water a day in order to consume the recommended daily allowance of iodine, calculate the concentration of the iodine in the water in
   • g/mL
   • ppm
   • M
   • % by mass of iodine
5. Assuming 10mL of the iodine solution from question 4 is run through the water-testing disk as described in the article above. Calculate the mass of iodine present in this sample in
   
   • grams
   • milligrams
   • micrograms
   • nanograms
6. Some water is held in contingency water containers (CWCs) which look like duffle bags and hold about 40kg of water each. Assuming each bag is treated with enough iodine to provide the recommended daily intake of iodine if an adult consumes 3L per day, calculate
   
   • the mass of iodine in each CWC in grams
   • the mass of iodine in each CWC in milligrams
   • the mass of iodine in each CWC in micrograms
     
   • the concentration of iodine in each CWC in g/mL
   • the concentration of iodine in each CWC in ppm
     
   • the concentration of iodine in each CWC in mol/L
     
   
   

Heavy Metal Pollution

Hard water contains calcium and magnesium cations which can be removed using a suitable ion exchange resin.
Heavy metal ions such as cadmium, copper, chromium, mercury, nickel, lead and zinc, may also be present in water at unacceptable levels. This is referred to as heavy metal pollution of water.
Run off from roads is a large source of heavy metal contamination in water:

• Lead: leaded petrol (gasoline), tire wear, lubricating oil and grease, bearing wear
• Zinc: tire wear, motor oil, grease, brake emissions, corrosion of galvanized parts
• Iron: car body rust, engine parts
• Copper: bearing wear, engine parts, brake emissions
• Cadmium: tire wear, fuel burning, batteries
• Chromium: air conditioning coolants, engine parts, brake emissions
• Nickel: diesel fuel and petrol (gasoline), lubricating oil, brake emissions

Many of these heavy metals form negatively charged complex ions in water.
For example, chromium can form the chromate ion, CrO₄²⁻, and the dichromate ion, Cr₂O₇^2-.
Existing water treatment processes to remove these negatively charged ions can be inefficient and expensive.

Chemists at the University of California, Santa Cruz, have now developed a new type of material that can soak up negatively-charged pollutants from water. The new material called SLUG-26 contains copper hydroxide ethanedisulfonate.

Copper hydroxide ethanedisulfonate has a layered structure of positively-charged two-dimensional sheets with a high capacity for holding onto negative ions. These positively charged sheets are made up of [Cu4(OH)6]2+ ions as shown to the right. Copper atoms are shown in green and oxygen atoms are shown in red. The ethanedisulfonate exists as a counteranion.

This material could be used to treat polluted water through an ion exchange process similar to water softening. SLUG-26 provides a positively-charged substrate that can exchange a nontoxic negative ion for the negatively-charged pollutants.
The researchers are currently focusing on the use of SLUG-26 to trap the radioactive metal technetium, which is a major concern for long-term disposal of radioactive waste. Technetium is produced in nuclear reactors and has a long half-life of 212,000 years. It forms the negative ion pertechnetate in water and can leach out of solid waste, making groundwater contamination a serious concern.

Reference
Honghan Fei, Scott R. J. Oliver. Copper Hydroxide Ethanedisulfonate: A Cationic Inorganic Layered Material for High-Capacity Anion Exchange. Angewandte Chemie, 2011; DOI: 10.1002/ange.201104200

Further Reading
Periodic Table
Oxidation States
Zeolites

Suggested Study Questions

1. Give the chemical symbol for each of the following elements:
   • calcium
   • magnesium
   • cadmium
   • copper
   • chromium
   • mercury
   • nickel
   • lead
   • zinc
   • technetium
2. Identify which group of the periodic table each of the metals above belongs to.
3. Give the oxidation state for the metal atom in each of the following compounds:
   • CrO₄²⁻
   • Cr₂O₇^2-
   • [Cu₄(OH)₆]²⁺
4. Zeolites can be used to soften hard water. Write an equation to describe the process in which calcium ions in hard water are exchanged for sodium ions.
5. Suggest some possible non-toxic anions that could be exchanged for the toxic pertechnetate anion using SLUG-26.
6. Write an equation to show how the pertechnetate anion could be exchanged for one of the non-toxic anions in question 5.
7. Describe some other possible uses, apart from the removal of pertechnetate anions, for SLUG-26.
   
   
   

Stable Foam

Foams often have detergent properties due to their particular texture and the molecules that make up the foam. These molecules, which must be dispersed in water to create foam, are called "surface-active." They are located spontaneously in water and air, so that very thin films of water can stabilize around air bubbles of foam with a special architecture. Due to such properties, various foams have numerous applications in cleaning, decontamination, cosmetics, battling pollution and Scientists have been studying a particular surface-active molecule known as 12-hydroxystearic acid which is produced from castor oil.

This molecule is insoluble in water but it becomes water soluble when a suitable salt is added. This surfactant is very special because even in small quantities, it produces abundant foam and, above all, remains stable for more than six months, in contrast with traditional surfactants that stabilize foams for only several hours.

At temperatures between 20 and 60°C, the surfactant disperses in water in the form of tubes that are several microns in size. The tubes form a structure that is perfectly stable and rigid in very thin films of water located between air bubbles, which explains the foam's resistance.
Above 60°C, the tubes merge into micelles, spherical assemblies that are a thousand times smaller (several nanometers). The previously stable foam then collapses because the rigid structure disappears. The researchers have demonstrated that this transition from an assembly of tubes to an assembly of micelles is reversible. If the foam's temperature is increased, its volume will diminish when micelles start to form, and if the temperature is again reduced to between 20 and 60°C, the tubes will form again and the form will re-stabilize (to regain the initial volume of the foam, air must be re-injected).

Reference
Anne-Laure Fameau, Arnaud Saint-Jalmes, Fabrice Cousin, Bérénice Houinsou Houssou, Bruno Novales, Laurence Navailles, Frédéric Nallet, Cédric Gaillard, François Boué, Jean-Paul Douliez. Smart Foams: Switching Reversibly between Ultrastable and Unstable Foams. Angewandte Chemie, 2011; DOI: 10.1002/ange.201102115

Further Reading
Synthetic Detergents
Soaps and Saponification
Functional Groups
Lipids

Suggested Questions:

1. Give the molecular formula for 12-hydroxystearic acid.
2. On the structural formula of 12-hydroxystearic acid identify the:
   • carboxyl functional group
   • hydroxyl functional group
3. Is 12-hydroxystearic acid a saturated or unsaturated fatty acid. Explain your answer.
4. Draw 2 structural isomers of 12-hydroxystearic acid.
5. Explain why 12-hydroxystearic acid is not very soluble in water.
6. Draw a structural formula for lithium 12-hydroxystearate, the lithium salt of 12-hydroxystearic acid.
7. What properties of lithium 12-hydroxystearate make it a common component in greases used in motor vehicles, aircraft and heavy machinery?
8. Explain how the properties listed above in question 7 relate to the chemical structure of lithium 12-hydroxystearate.
9. Design experiments to test:
   
   • the stability of the foams formed by a range of household detergents
   • the stability of foam at different temperatures
   • the stability of foam in the presence of different salts
     
   
   

Molecular Motor

The Guinness World Record for the smallest electric motor currently stands at 200 nanometers, a human hair is about 300 times wider! Now Chemists at Tufts University's School of Arts and Sciences say they have developed the world's first single molecule electric motor, just 1 nanometer in diameter.

The molecular motor was produced when a butyl methyl sulfide molecule had been placed on a conductive copper surface and given an electrical charge. This sulfur-containing molecule had carbon and hydrogen atoms radiating off to form what looked like two arms, with four carbons on one side and one on the other. These carbon chains were free to rotate around the sulfur-copper bond.

The team determined that by controlling the temperature of the molecule they could directly impact the rotation of the molecule. Temperatures around 5 K, or about -450ºF, proved to be the ideal to track the motor's motion. The motor spins much faster at higher temperatures

Reference
Heather L. Tierney, Colin J. Murphy, April D. Jewell, Ashleigh E. Baber, Erin V. Iski, Harout Y. Khodaverdian, Allister F. McGuire, Nikolai Klebanov, E. Charles H. Sykes. Experimental demonstration of a single-molecule electric motor. Nature Nanotechnology, 2011; DOI: 10.1038/NNANO.2011.142

Further Reading
SI Unit Conversions
Temperature Conversions
Nomenclature
Molecule Polarity
Intermolecular Forces
Molecular Mass (formula weight) Calculations
Percentage Composition
Empirical and Molecular Formula

Study Questions:

1. Convert 200 nanometers to a diameter in
   • meters
   • micrometers
   • millmeters
   • decimeters
2. Form the information in the article above:
   • What is the diameter of a human hair in nanometers?
   • What is the size ratio of the molecular motor to a human hair?
3. Convert the following temperatures:
   • 5K to ^oC
   • 0K to ^oC
   • 100^oC to K
   • 25^oC to K
     
4. On the molecular structure of butyl methyl sulfide:
   • identify the butyl group
   • identify the methyl group
5. For a molecule of butyl methyl sulfide:
   • write the molecular formula
   • give the empirical formula
     
   • calculate the molecular mass
   • calculate the percentage composition
     
   
   
6. Is butyl methyl sulfide a polar or non-polar molecule? Explain your answer.
7. Do you expect butyl methyl sulfide to be water soluble? Explain your answer.
   
   
   
   

What is the pH of water?

The Brisbane Courier Mail ran a lift-out in their newspaper promoting science week on Tuesday 2^nd August 2011, and, within that, they included a Science Quiz of 20 questions.
Question 13 (an ill omen perhaps?) was, "What is the pH value of water?"

Now this is the kind of question that stumps a lot of High School Chemistry students, and unfortunately, most of the Australian population. So it was with some trepidation that I ventured to see what answer the Courier Mail came up with, and was not at all surprised to find out they got it wrong. Their answer was, ofcourse, 7. Feeling quite strongly about the perpetration of this misconception, especially in an attempt to promote Science Week, I emailed them to explain why the pH of water cannot be said to be 7. Unfortunately my explanation must have been insufficient, or the misconecption just too strongly believed, because they then changed their answer to the equally incorrect "the pH of neutral water is 7".

The September 2011 issue of AUS-e-NEWS takes a look at the dissociation of water and indicators.
To subscribe to AUS-e-NEWS, AUS-e-TUTE's newsletter, email
using subscribe as the subject line.

Ethanol in Mouthwash

"A company that makes oral cancer detection tests is suing Listerine-maker Johnson & Johnson over claims the company stymied sales of the tests to protect the image of its mouthwash.
....... Some studies have linked mouthwashes with high alcohol content to cancer ... "
(http://www.smh.com.au/lifestyle/beauty/listerine-cancer-claim-triggers-court-battle-20110829-1jh63.html)

At concentrations above 60% by volume, ethanol is an antiseptic that kills bacteria, fungi and some viruses by denaturing their proteins and dissolving their lipids. The ethanol content of a mouthwash can be around 20% by volume, which is substantially greater than the alcohol content of most wines at around 12% v/v, but less than that required to act as an antiseptic.

One of the antiseptic agents present in mouthwash is thymol, shown to the right. The concentration of thymol in mouthwash can be about 0.0063% w/v. Thymol is only slightly soluble in water, but it is very soluble in ethanol.

Typically, a person will use 20mL of mouthwash twice a day to rinse the mouth, and will spit out the mouthwash rather than swallowing it.

Further reading:
Lipids
Proteins
Functional Groups
Molecular Mass Calculations
Weight/Volume Concentration

Study Questions:

1. Give the molecular and structural formula for ethanol.
2. Explain what Chemists mean when they refer to the denaturing of a protein.
3. What is a lipid?
4. What are the elements that are present in all proteins?
5. What are the elements that are present in all lipids?
6. Give the molecular formula for thymol.
7. On the structural formula of thymol, circle the functional groups present.
8. What is the molecular mass (formula weight) of thymol?
9. What mass of thymol would be present in 20mL of mouthwash?
10. How much ethanol would be present in a 750mL bottle of mouthwash?
11. How much ethanol would be present in a 750mL bottle of wine?
12. In Australia, a standard drink is defined as one that contains 10g of pure ethanol. How many standard drinks are present in:
    • 750mL bottle of wine?
    • 750mL bottle of mouthwash?

Diamond Planet Discovered

Scientists from Australia, Germany, Italy, the UK and the USA, have detected a companion planet for Pulsar J1719-1438 in our Milky Way, and they believe that this companion planet could be made of diamond. The planet is thought to be small, less than 60,000km in diameter, with a mass slightly greater than that of Jupiter, about 2 x 10²⁷kg.
P1719-1438 and its planet are so close together that the planet is most likely to be a 'stripped-down' white dwarf, that is, one that has lost its outer layers and over 99.9% of its original mass. Based on the planet's orbiting times, the scientists think that this remnant is likely to be made up mostly of carbon and oxygen, while its high density suggests that the material present is crystalline, which leads them to believe that the planet could contain a sizable proportion of diamond.

Graphite can be transformed into diamond under pressures of more than about 4GPa, as is shown in the simplified phase diagram on the right. On Earth, diamonds can be formed in the mantle where the pressure is great enough to transform carbon sources into diamonds. Diamonds can also form when a meteorite impacts on the Earth because the impact creates a zone of high pressure and temperature in which carbon can be transformed into diamond.

Reference
M. Bailes, S. D. Bates, V. Bhalerao, N. D. R. Bhat, M. Burgay, S. Burke-Spolaor, N. D'Amico, S. Johnston, M. J. Keith, M. Kramer, S. R. Kulkarni, L. Levin, A. G. Lyne, S. Milia, A. Possenti, L. Spitler, B. Stappers, W. van Straten. Transformation of a Star into a Planet in a Millisecond Pulsar Binary. Science, 2011; DOI: 10.1126/science.1208890

Further Reading
Mass Conversions
Density Calculations
Allotropes

Study Questions

1. Convert 60,000km to a distance in:
   • meters
   • centimeters
     
   • millimeters
     
2. Convert 2 x 10²⁷kg to a mass in
   • grams
   • megagrams
   • gigagrams
     
3. What is the approximate radius of of the planet in cm?
4. What is the volume of the planet in cm³ (assuming the planet is spherical)?
5. Calculate the approximate density of the newly discovered planet (in g/cm³).
6. Convert 4GPa to a pressure in:
   • kilopascals
   • pascals
   • megapascals
   • atmospheres
     
   
   
7. Using the phase diagram for carbon in the article above:
   • What is the minimum temperature and pressure required to produce liquid carbon from gaseous carbon?
   • What is the maximum pressure at which graphite can exist?
   • What is the maximum temperature at which graphite can exist?
     
   • How many phases of carbon are present at 4500K and 0.01GPa?
   • What is the triple point for diamond?
     
   
   

Arsenic in Air, Hair and Water

On Saturday 20^th August 2011, the Sydney Morning Herald reported that the chemical company Orica "discharged up to 1.2 megalitres of effluent containing traces of arsenic above its environmental protection licence cap yesterday afternoon".
Arsenic is toxic, it disrupts the transport of energy within cells and metabolism. The minimal lethal dose of arsenic in adults is about 1mg per kilogram of body mass per day, but arsenic trioxide is about 500 times more toxic than pure arsenic.

The Romans used arsenic compounds, especially naturally occurring arsenic sulfides, as medicines. The Roman writer Dioscorides (40-90) wrote in De Materia Medica (Medical Matters) that arsenic sulfides could be used to treat warts and skin eruptions, but warned that the remedy could cause the patient's hair to fall out! It is believed that Agrippina used arsenic trioxide to murder her husband so that she could marry her uncle, the Emporer Claudius.
At about the same time, the Chinese were using arsenic compounds to kill flies and rodents while Indians were using them to preserve paper from attack by insects.

In medieval Europe, arsenic trioxide was being used to treat malaria, while arsenic sulfides were used to treat arthritis, asthma, tuberculosis, and diabetes.

In 1809, Dr. Fowler's Solution first appeared in the London Pharmacopoeia, and it was considered to be a cure for almost everything! Fowler's solution was a mixture of potassium arsenite in lavender water. It was prepared by dissolving 10g of arsenic trioxide and 7.6g of potassium hydrogen carbonate in 1L of distilled water, then adding a little alcohol and lavender oil. The maximum single dose recommended was 0.5mL of Fowler's Solution which could be added to a glass of water or wine.

Arsenic was very common in European households up until the late 19^th century.
Arsenic was being used to provide brilliant colours in dyes and paints:

• yellow orpiment, As₂S₃ (a mineral in use since Ancient times)
  
• red realgar, As₄S₄ (a mineral in use since Ancient times)
  
• Scheele's Green, copper arsenite, CuHAsO₃ (first produced in 1778)
• Emerald Green, a combination of copper acetate and copper arsenite (first produced in 1822)

In the 19^th century, arsenic-based green colours were being used to colour paint, wallpaper, soap, lampshades, children's toys, candles, soft furnishings, and even food. By the late 19th century, Gosio's disease, sickness resulting from breathing the air in rooms decorated with arsenic compounds, was identified. The deadly vapour was not identified as trimethylarsine until the 1930's.

Napoleon Bonaparte died on 6^th May 1821 at Longwood House on Saint Helena. Samples of Napoleon's hair were analysed in 1995 and were found to contain between 33ppm and 17ppm of arsenic, the maximum "safe" limit is currently considered to be about 3ppm and the normal level is about 1ppm. While some people believe that Napoleon was deliberately poisoned,it is possible that green furnishings at Longwood House could be to blame for the high levels of arsenic in his body.

Arsenic has also been discovered in the hair of "mad" King George III of Great Britain who died in 1820. In 2003, samples of the King's hair found in the Science Museum London were analyzed and found to contain about 17ppm arsenic.

in 1904, Julius Nieuwland added an aluminium chloride catalyst to a mixture of acetylene and arsenic trichloride to produce an arsenic compound that came to be known as Lewisite. Unfortunately Nieuwland had taken no safety precautions so he breathed in some of the vapour, was taken ill and spent the next few days in hospital. During World War I, Winford Lewis heard about Nieuwland's earlier experiment, and he learnt how to produce the toxic compound under carefully controlled conditions so that it could be used as a weapon. By November 1918, the USA was shipping deadly Lewisite to Europe. Lewisite was then used by the Japenese against the Chinese in Manchuria in 1940, and by Saddam Hussein in the Iran-Iraq war in the 1980's.

Tube wells, drilled in the 1970's in West Bengal, India and Bangladesh, were installed in a drive by the United Nations Children's Fund (UNICEF) to provide safe drinking water for a population that had traditionally taken its water from contaminated streams, rivers, and ponds, and therefore suffered from water-borne diseases such as gastroenteritis, typhoid and cholera. By 1983 the population, more than 30 million people, were showing signs of arsenic poisoning. The water in many of the wells had arsenic levels of between 50ppb and 4000ppb. At the time, the World Health Organisation (WHO) stated that drinking water should not contain more than 10μg/L.

In the 20th century, copper arsenite, also known as Paris Green, and lead arsenate have been used as a horticultural spray to kill moths on apple trees, but these compounds have now been phased out. Chromium copper arsenate, used to treat wood to prevent it rotting and being eaten by termites, has been phased out in some countries like Australia, Canada and the USA, but is still being used in others. In the electronics industries, arsenic is added to silicon and germanium semiconductors to provide electrons to the crystal lattice. Gallium arsenide is a semi-conductor which has the ability to convert electric current to laser light, so this is a growing use for the world's arsenic.

Further Reading
Volume Conversions
Parts per Million Concentration
W/V %
Molarity
Writing Ionic Formulae
Oxidation States (Numbers)

Study Questions:

1. Convert 1.2 megalitres to a volume in
   • litres
   • kilolitres
   • gigalitres
   • millilitres
2. "The minimal lethal dose of arsenic in adults is about 1mg per kilogram of body mass per day". Calculate the mass of the dose of arsenic that would be lethal in each case below:
   • 1 dose given in 1 day to a man weighing 90kg
   • 1 dose given in 1 day to a woman weighing 65kg
   • 1 dose given in 1 day to a child weighing 30kg
   • 1 dose given 3 times a day with meals to a person weighing 70kg.
3. The arsenite ion has the formula AsO₃^3- and the arsenate ion has the formula AsO₄^3-.
   • Write the formula for potassium arsenite
   • Write the formula for potassium arsenate
   • Write the formula for calcium arsenite
   • Write the formula for barium arsenate
   • Write the formula for ammonium arsenate
   • Write the formula for copper (II) arsenite
   • Write the formula for lead (II) arsenate
     
4. Give the oxidation state (number) of arsenic in each of the following:
   • AsO₃^3-
   • AsO₄^3-
   • As₂S₃
   • As₄S₄
   • HAsO₃^2-
   • As₂O₃
   • AsCl₃
5. Calculate the concentration of arsenic ions in mol/L in 1L of Fowler's Solution using the recipe provided in the article (assume all the arsenic present is in the form of arsenic ions).
6. For a 0.5mL dose of Fowler's Solution, calculate
   • the mass of arsenic present in grams
   • the mass of arsenic present in milligrams
   • the concentration of arsenic in parts per million
7. Assuming 10g hair samples were tested for arsenic
   • What is the mass of arsenic present in a healthy persons hair if the normal level is 1ppm?
   • The safe limit for arsenic in hair is 3ppm, what mass of arsenic is this equivalent to ?
   • Napoleon's hair was found to contain between 17ppm and 33ppm arsenic. Convert each of these concentrations to a mass of arsenic.
8. For the water tested in the Asian tube wells:
   • convert 4000ppb to a concentration in ppm
   • calculate the mass of arsenic in 1L of water if the concentration is 50ppb
   • convert the safe limit for arsenic in drinking water, 10μg/L, to a concentration in mol/L
   • calculate the mass of arsenic present in 1L of drinking water that contains 10μg/L arsenic
     

Reference

http://www.smh.com.au/environment/orica-admits-arsenic-spill-into-river-20110819-1j2nz.html#ixzz1Vcq8n2jf

Bone Composition

Bone is a kind of specialized connective tissue providing a supportive framework for the body. Bones are continually being remodeled during the life of the body so they can be used to determine the age of a body.

About 70% of bone is made up of calcium hydroxyapatite, 3Ca₃(PO₄)₂.Ca(OH)₂.
The crystals of calcium hydroxyapatite in bone are very small, about 5nm x 5 nm x 40nm.
The total surface area of calcium hydroxyapatite in bone is extremely large, about 40 hectares in the skeleton of a 70kg man.
About 10% of bone is made up of water, and the other 20% is made up of organic compounds such as collagen. The term collagen refers to a group of proteins, and is the most abundant protein found in mammals, about 30% of all the protein in the body is collagen.

The bone of very young people, less than 4 years of age, is called woven bone because the collagen fibres are interwoven and run in all directions just like a piece of felt, and the bone contains large holes like Swiss cheese.

The bones of bones of adults include lamellar bone which has collagen fibres organized into layers or sheets known as lamellae. These are usually built up around blood vessels like the layers of an onion. This produces compact bone.
Adult bones also include trabecular (cancellous, spongy) bone. The bone itself is in the form of little beams (trabeculae) which are about 200μm thick. The spaces in the bone can contain marrow.

Osteoporosis refers to a decrease in the amount of bone tissue which results in an increased tendency for the bone to fracture. The shape and size of the bone doesn't change, but the little beams, the trabeculae, become thinner and some may disappear altogether.
Astronauts in space can also display a decrease in the amount of bone tissue because there is less load, and therefore less stress, on their bones in space.

Aerobic and resistance training increase the density. Bone is deposited when there is load, and stress, applied to the bone.

Scientists at the Rensselaer Polytechnic Institute have developed a new technique to analyze the bone matrix. This technique provides information about the concentration of different proteins in the bones, which can be used to determine how the bone was formed, how it has been modified over time, and, if the bone is prone to fracture.

Reference
G. E. Sroga, L. Karim, W. Colon, D. Vashishth. Biochemical characterization of major bone-matrix proteins using nanoscale-size bone samples and proteomics methodology. Molecular & Cellular Proteomics, 2011; DOI: 10.1074/mcp.M110.006718

Further Reading
Molecular Mass (Formula Weight)
Percentage Composition
Unit Conversions
Density
Mass-Mole Calculations

Study Questions

1. Calculate the molecular mass (formula weight) of calcium hydroxyapatite.
2. Calculate the percentage composition of calcium hydroxyapatite.
3. 1 hectare is 1,000m², what is the surface area in m² of calcium hydroxyapatite crystals in a 70kg man?
4. If you laid out all the calcium hydroxyapatite crystals in the bones of the 70kg man above onto a football field, how many football fields would you need? (Assume a football field is about 6,000m²)
5. The little beams in trabecular bone are 200μm thick. Convert this to a thickness in
   
   • meters
   • millimeters
   • nanometers
   • angstroms
6. The density of a bone in the leg is about 2g/cm³. 70% of bone is made up of calcium hydroxyapatite. Calculate:
   • the mass of calcium hydroxyapatite present in a 500cm³ bone sample
   • the moles of calcium hydroxyapatite present in the same bone sample
   • the percentage of calcium present in the same bone sample
   • the mass of calcium present in the same bone sample
   • the mass of water present in the same bone sample
   • the mass of organic compounds present in the same bone sample
     
7. Which type of bone, woven bone or lamellar bone, has the greatest density? Explain your answer.
8. Will the bones of a person suffering from osteoporosis be more or less dense than the bones of an athletic young adult? Explain your answer.
   
   

DNA in Space

Scientists have evidence that some building blocks of DNA, the molecule that carries the genetic instructions for life, found in meteorites were most likely to have been created in space.
The DNA building blocks present in the meteorites are called nucleobases or nucleotide bases, a group of nitrogen-based molecules that are required in the formation of nucleotides, and nucleotides are the molecules that make up DNA. The primary nucleobases in DNA are cytosine, guanine, adenine and thymine.

For the first time, we have three lines of evidence that together give us confidence these DNA building blocks found in meteorites actually were created in space:

1. In two of the meteorites, trace amounts of three molecules related to nucleobases: purine, 2,6-diaminopurine, and 6,8-diaminopurine; were discovered for the first time. 2,6-diaminopurine, and 6,8-diaminopurine are almost never used in biology so these can't be due to contamination from terrestrial sources.
2. The amounts of the two nucleobases adenine and guanine found in DNA, plus hypoxanthine and xanthine which are similar to the nucleobases but not found in DNA, that were found in terrestrial ice samples from near the Antarctic meteorites were much lower, parts per trillion, than in the meteorites, where they were generally present at several parts per billion. This strongly suggests that terrestrial contamination was not responsible for the presence of these molecules in the meteorites.
3. The adenine, guanine, hypoxanthine and xanthine were produced in a completely non-biological reaction. In the lab, these same molecules were generated in non-biological chemical reactions containing hydrogen cyanide, ammonia, and water. This provides a plausible mechanism for their synthesis in the asteroid parent bodies, and supports the notion that they are extraterrestrial

Reference
NASA (2011, August 9). DNA building blocks can be made in space, NASA evidence suggests. ScienceDaily. Retrieved August 11, 2011, from http://www.sciencedaily.com­ /releases/2011/08/110808220659.htm

Further Reading
DNA
Functional Groups

Study Questions

1. What does the abbreviation DNA stand for?
2. Give the accepted abbreviations for each of the following nucleobases:
   • adenine
   • guanine
   • cytosine
   • thymine
3. Draw a structural formula for each of the nucleobases above.
4. On the structural formulae above, circle the functional groups present.
   
5. Below is the structural formula for hypoxanthine:
   
   Which nucleobase is it most similar to? Explain your answer.
6. Guanine can form 3 hydrogen bonds with cytosine. How many hydrogen bonds could be formed between hypoxanthine cytosine. Use a diagram to explain your answer.
7. The structure of 2,6-diaminopurine is shown below:
   
   Circle the two amine functional groups.
8. What functional groups would be found in a molecule of 6,8-diaminopurine?
9. Give the molecular formula for each of the following molecules:
   • hydrogen cyanide
   • ammonia
   • water
10. Why do you think scientists would try to make the nucleobases out of hydrogen cyanide, ammonia, and water in the laboratory?
    

Hydronium Ions in Fermentation

Ethanol or ethyl alcohol (C₂H₅OH) can be produced from glucose (C₆H₁₂O₆) by fermentation using an enzyme as a catalyst:

C6H12O6

enzyme -------->

2 C2H5OH + 2 CO2

Chemists are very interested in studying this reaction because it has the potential to convert the sugars in woody biomass into alcohols which can be used as a fuel in place of non-renewable fuels obtained from petroleum. It is known that the enzyme in yeast which is commonly used in the production of ethanol loses its effectiveness when the pH of the reaction mixture is lowered.

In aqueous solutions, as soon as protons (H⁺) are released by an acidic species they bond with water molecules (H₂O) to form hydronium ions (H₃O⁺) :

H⁺ + H₂O → H₃O⁺

and pH is a measure of the hydronium ion concentration:
pH = -log[H₃O⁺]although we often think of this as being the same as a measure of the proton concentration:
pH = -log[H⁺]since we reasonably expect all the protons to have reacted with water molecules to form hydronium ions.

Los Alamos National Laboratory scientists substituted hydrogen in their enzyme samples with deuterium, an isotope of hydrogen (hydrogen-2). Unlike hydrogen-1 atoms, deuterium atoms provide a clear signal when bombarded with neutrons so they are visible to X-rays, this fact can be used to study the enzyme catalyzed process of fermentation.

The scientists found that as the pH fell below 6, hydronium ions (H₃O⁺) that are vitally important in the conversion of the sugar molecule into its fermentable form suddenly became dehydrated.
H₃O⁺ → H₂O + H⁺
The space in the enzyme occupied by the relatively large hydronium ion collapsed into a tiny volume occupied by the remaining proton (H⁺). This spatial change in the molecular structure prevented the sugar from being attacked by the enzyme.

The observed phenomenon provided an answer about why pH plays such an important role in the process and renders the enzyme inactive under acidic conditions. More important, it definitively illustrated that the hydronium ion plays a key role in the transport of protons in these types of biochemical systems.

Reference
Andrey Y. Kovalevsky, B. L. Hanson, S. A. Mason, T. Yoshida, S. Z. Fisher, M. Mustyakimov, V. T. Forsyth, M. P. Blakeley, D. A. Keen, Paul Langan. Identification of the Elusive Hydronium Ion Exchanging Roles with a Proton in an Enzyme at Lower pH Values. Angewandte Chemie International Edition, 2011; 50 (33): 7520 DOI: 10.1002/anie.201101753

Further Reading:
Mass-Mole Calculations
Gas Volume Calculations
Molarity Calculations
Yield Calculations
pH Calculations
Enzymes

Study Questions:

1. A Chemist undertook a fermentation experiment using 10g of glucose dissolved in 1L of water.
   • How many moles of glucose were present in the solution?
   • What was the concentration of the initial glucose solution?
   • What is the maximum yield of ethanol that could be produced from this reaction mixture?
   • If the actual yield of ethanol was 4% by mass, how many moles of ethanol was produced?
   • If the actual yield of ethanol was 4% by mass at 25^oC, what volume of carbon dioxide gas was be produced?
2. Assuming the fermentation of glucose reaction occurs at a constant temperature of 25^oC
   • Calculate the concentration of hydronium ions present in a reaction mixture with a pH of 6.
   • Calculate the concentration of hydroxide ions present in a solution with pH of 6
   • Calculate the pOH of a solution with a pH of 6.
3. What is meant by the term catalyst?
4. What is meant by the term enzyme?
5. Explain why the hydronium ion is larger than the hydrogen ion.
6. Would the hydronium ion be larger or smaller than a water molecule? Explain your answer.
7. How would you define the term isotope?
8. Explain why deuterium is considered to be an isotope of hydrogen.
   
   
   

Isobutene

Isobutene and isobutylene are other names used for the organic compound with the IUPAC name 2-methylpropene. 2-methylpropene is one of the four structural isomers of butene and it exists as a highly flammable, colourless gas at standard temperature and pressure. Isobutene can be converted into fuel additives that increase the octane rating and prevent engine knocking.
Addition polymerization of isobutene results in polyisobutene (PIB) a rubbery substance which is used in the manufacture of tires, adhesives, ball bladders, caulks and sealants, cling film, rubber modification, fuel additives, and chewing gum.

Researchers at the Department of Energy's Pacific Northwest National Laboratory and at Washington State University have developed a new catalyst material composed of zinc oxide and zirconium oxide that will convert bio-ethanol into isobutene in one production step.
If the catalyst was composed only of zinc oxide, the ethanol was mostly converted into acetone (the chemical used in nail polish remover).
If the catalyst was composed only of zirconium oxide, the ethanol was mostly converted into ethylene (the chemical made by plants that ripens fruit).
When the catalyst is composed of a 1:10 ratio of zinc oxide to zirconium oxide, 83% of the ethanol was converted into isobutene.

Reference
Junming Sun, Kake Zhu, Feng Gao, Chongmin Wang, Jun Liu, Charles H. F. Peden, Yong Wang. Direct Conversion of Bio-ethanol to Isobutene on Nanosized ZnxZryOzMixed Oxides with Balanced Acid–Base Sites. Journal of the American Chemical Society, 2011; 133 (29): 11096 DOI: 10.1021/ja204235v

Further Reading
Naming Carbon Compounds
Structural Isomers of Alkenes
Ideal Gas Law
Polymers and Polymerization
Fuel Definitions
Energy Profiles

Study Questions

1. Give the molecular formula and structural formula for 2-methylpropene.
2. Draw the structural formula for all four structural isomers of butene.
3. Write an equation to represent the polymerization of 2-methylpropene to polyisobutene.
4. Use diagrams to show why the polymerization reaction above is considered to be an addition polymerization reaction.
5. On the diagram produced in response to question 4, clearly label the monomer and polymer compounds.
   
6. Give likely formulae for both zinc oxide and zirconium oxide.
7. Give the IUPAC name, the molecular formula and the structural formula, for each of the following:
   • isobutene
     
   • acetone
   • ethylene
8. Write equations for each of the following catalyzed reactions:
   • the conversion of ethanol into acetone
     
   • the conversion of ethanol into ethylene
9. Which of the following compounds could undergo addition polymerization? Justify your answer.
   
   • acetone
   • ethylene
10. Name the products of any successful addition polymerization in question 8.