Molecular Machines

People use machines to perform tasks that fall beyond our capacities.

Since the Industrial Revolution, the complexity and number of machines we use has increased.

At the Annual Meeting of the American Physical Society in 1959, physicist and 1965 Nobel Laureate in Physics, Richard Feynman talked about the possibility of building small machines from atoms.

He returned to this idea in a lecture in 1984 he asked, "How small can you make a machine?".

But by then Chemists had already taken the first tentative steps towards building molecular machines.

The 2016 Nobel Prize in Chemistry has been awarded to Jean-Pierre Sauvage, Sir J. Fraser Stoddart and Bernard L. Feringa, whose research has led to the development of molecular machines...

Learn more in this edition of AUS-e-NEWS.

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Fatty Acids

Do you want to answer any of the questions listed below:

• What is a fatty acid?
• What are the structures and formulae of common fatty acids?
• What is a saturated fatty acid?
• What is an unsaturated fatty acid?
• What is a monounsaturated fatty acid?
• What is a polyunsaturated fatty acid?
• What determines the melting point and solubility of a fatty acid?
• What is an essential fatty acid?
• What is an omega-3 fatty acid?
• What is an omega-6 fatty acid?

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Vitamins

Does it seem that dieticians and nutrition experts seem to make a huge fuss about eating foods that seem to contain infinitesimal amounts of those mysterious substances known as vitamins?
Well, there is some good, sound chemistry behind why this is so.
Find out about the chemistry of vitamins with AUS-e-TUTE's newest set of resources!

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Gravimetric Analysis

Gravimetric analysis can be used to determine the quantity of an ion present in a solution.
This can be done by adding a reagent that causes the ion under investigation to form an insoluble compound (a precipitate) that precipitates out of the solution.
AUS-e-TUTE has "free-to-view" tutorials currently available on :

1.  Determining the percentage by mass of sulfate in a lawn fertiliser
2.  Determining the concentration of chloride ions in water

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Salt from Seawater

About 200 Mt of sodium chloride are consumed every year in the world.

Some sodium chloride will be added to food, some will be used as a highway de-icing agent in cold climates, but most of it will be used in industries such as leather tanning, dye manufacturing, paper production, and in the production of other chemicals such as sodium carbonate, sodium hydroxide and chlorine.

The largest source of sodium chloride is the world's oceans.

So, how hard can it be to produce sodium chloride?

Surely you just evaporate the water off seawater and "hey presto", sodium chloride!

In reality, it's not quite that simple .....

Learn more in the September 2016 edition of AUS-e-NEWS.

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Coral Killing Sunscreens

More than a year ago, a study involving marine scientists from Virginia, Florida, Israel, the US National Aquarium and the US National Oceanic and Atmospheric Administration, identified a common chemical component of sunscreens capable of damaging coral reefs.
This chemical is commonly known as oxybenzone and its structure is shown below:

This molecule has the systematic IUPAC name of (2-hydroxy-4-methoxyphenyl)(phenyl)methanone
Notice how every carbon atom (except that of the terminal methyl group, the carbon atom of the methoxy group) is involved in a double bond?
This kind of arrangement leads to some interesting properties. One of these properties is that molecules like this one are good at absorbing UV light. So, oxybenzone is added to products such as plastics, sunscreens, hairsprays, nail varnish and cosmetics like lipstick and mascara, as a UV filter.
Sunscreen lotion can contain between 1 and 10% oxybenzone.
Unfortunately, oxybenzone enters the water when people wearing sunscreens or other cosmetics decide to go for a swim. Researchers estimate that between 6,000 and 14,000 tonnes of sunscreen lotion are emitted into the waters of coral reefs each year.
The same property that makes it ideal as a sunscreen makes it a catastrophe for our coral reefs! Blocking UV light to baby corals causes growth deformities, and worse, the coral becomes encased in its own skeleton and dies.
In 2016, a study of Hawaii's sea waters found the oxybenzone concentration ranged from 0.8 to 19.2 µg/L. A previous study found that oxybenzone concentrations as low as 0.062 µg/L could harm the coral.
Hawaii's government asked swimmers, surfers and divers to avoid using sunscreens that contain oxybenzone as a measure towards protecting their reef.

Reference:
Hawaii targets sunscreens with oxybenzone 

Suggested Study Questions:

1. Draw a molecule of oxybenzone, and, locate and name each functional group. 
2. Give the molecular formula for oxybenzone.
3. Calculate the molar mass of oxybenzone.
4. Draw the 2-dimensional structural formula for oxybenzone.
5. Oxybenzone readily dissolves in ethanol. Explain how oxybenzone can dissolve in ethanol.
6. Oxybenzone does not dissolve in water. Explain why oxybenzone dissolves in ethanol but not in water.
7. Given the data in the article, calculate the mass of oxybenzone that could be emitted into coral reef waters each year.
8. Convert the following concentrations of oxybenzone to concentrations in parts per million
   • 0.062 µg/L
   • 0.8 µg/L
   • 19.2 µg/L
9. Convert the following concentrations of oxybenzone to concentrations in moles per litre (molarity)
   • 0.062 µg/L
   • 0.8 µg/L
   • 19.2 µg/L
10. Assume a 375 g tube of sunscreen lotion contains 10% by mass oxybenzone. Use the data in the article to calculate an "average" number of tubes of sunscreen that washed into the ocean each year. Justify your answer.

Titanium Gold Alloy

Titanium is the metal used to replace hip and knee joints because it is strong, resistant to wear, and, is nontoxic.

Before titanium was used to replace hips and knees, stainless steel was used.
The density of stainless steel used to make replacement hips and knees is about 7.8 g cm³. The density of titanium metal is 4.506 g cm³, about half the density of stainless steel. This means that a replacement joint made out of titanium will weigh less than the same replacement joint made out of stainless steel.
Titanium is also strong. The strength of the material used to replace hip and knee joints is important because you do not want your new joint to bend or break or under strain.

Titanium has a melting point of 1670°C and a boiling point of 3287°C, which means it remains solid over the range of temperatures humans are exposed to. This is important because you want your new hip or knee replacement to remain a solid!
Naturally occurring titanium is made up of a number of isotopes, all of which are stable so they do not undergo nuclear decay. This is important because it means that there is no loss of titanium mass due to radioactive decay, and there is no fear of damage to cells from the emission of radiation.

isotope	atomic mass	abundance
46Ti	45.953	8.25
47Ti	46.952	7.44
48Ti	47.948	73.72
49Ti	48.948	5.41
50Ti	49.945	5.18

Titanium metal will react with water, halogens and dilute hydrochloric acid, but only if the temperature is elevated well above body temperature. Similarly, titanium metal will react with oxygen in a combustion reaction at elevated temperatures. Titanium metal does not appear to react with bases at all. Therefore, titanium is unlikely to react with substances found in the human body.

Researchers at Rice University have found that alloying titanium with gold can produce an even better material to use for replacement hips and knees. Mixing titanium and gold in the ratio of 3:1 at high temperature produces an alloy that is 3 times harder than steel and 4 times harder than the pure titanium commonly in use for hip and knee replacements. The atoms of titanium and gold in this alloy are packed in a cubic arrangement, an arrangement that is usually associated hardness. The structure of this alloy is shown below:

This titanium gold alloy has been found to be even more biocompatible that pure titanium.
The researchers intend to undertake further studies to investigate whether using chemical dopants might improve the alloy's hardness even further.

Reference:
Rice University. "Titanium and gold equals new gold standard for artificial joints: Titanium-gold alloy that is 4 times harder than most steels." ScienceDaily. ScienceDaily, 20 July 2016. 

Further Reading
Metals and Non-metals 
Density
Isotopes
Relative Atomic Mass
Alloys

Suggested Study Questions

1. Titanium and gold are both metallic metallic elements.
   • What are the physical properties common to most metallic elements?
   • What are the chemical properties common to most metallic elements?
2. Draw up a table of the physical properties of titanium.
3. A typical knee replacement made out of titanium has a mass of 560 g.
   • Calculate the volume of the titanium knee replacement.
   • Calculate the mass of the same knee replacement if it were made out of stainless steel
4. Define the term isotope.
5. Determine the number of protons in the nucleus of an atom of each of the isotopes of titanium listed in the article above.
6. Determine the number of neutrons in the nucleus of an atom of each of the isotopes of titanium lists in the article above.
7. Which is the most abundant isotope of titanium? Explain your answer.
8. Use the data in the article above to calculate the relative atomic mass of naturally occurring titanium.
9. Given the atomic radius of titanium is  176 pm (1.76 x 10^-10 m) and the atomic radius of gold is 174 pm (1.74 x 10^-10 m), do you think the alloy of titanium and gold discussed in the article above is an interstitial alloy or a substitutional alloy? Explain your answer.
10. Consider the structure of the titanium gold alloy shown in the diagram in the article above.
    • The blue balls represent which atoms of which element?
    • The red balls represent which atoms of which element?

Sticky Surfactant?

 How often have you found that, no matter how hard you try, it is impossible to get that last bit of detergent out of the plastic bottle? Do you turn the bottle upside down and wait, letting the cleaning stuff flow to the bottom, but then find there is still some left no matter how hard you squeeze the bottle? Do you then try adding a bit of water and shaking it so that you can extract just a little bit more of it out of the bottle? And then, do you eventually give up and finally chuck the bottle away, still containing a very small amount of the cleaning product?
Well, if you find this sticky surfactant problem unsatisfactory, you aren't alone!
 The reason why it is so hard to remove ALL the detergent from the bottle is the same reason why the detergent makes a good cleaning product, that is, surfactant molecules have a long non-polar chain that attracts other non-polar substances like oils and grease, and a polar or ionic head that attracts other polar substances like water. So, if you pour a detergent, containing surfactant molecules, into a non-polar plastic container like polyethylene or polypropylene, the non-polar parts of the surfactant molecule will be attracted to the non-polar surface of the bottle making it hard to get all the surfactant molecules out of the bottle.

But scientists at The Ohio State University have now developed a way to make the plastic bottles so that ALL your shampoo or "liquid" detergent will flow out of the bottle. It involves spray-coating the surface of the plastic with a solvent and ultrafine silica nanoparticles. The solvent softens the plastic enabling the silica to be embedded in the  surface formed "Y" shaped channels a few micrometers high and a few micrometers apart. The branches of the "Y" shapes overhang the plastic surface at an angle of less than 90 degrees resulting in trapped air. Surfactant molecules are then in contact with air rather than plastic so that they can form spherical beads that will roll off.

The university hopes to further develop this process and license the coating technique to manufacturers, not just for shampoo bottles, but for other plastic products that have to stay clean, such as biomedical devices or catheters.

Reference: 

Ohio State University. "Shampoo bottle that empties completely, every last drop." ScienceDaily. ScienceDaily, 27 June 2016.

Further Reading:

Soaps
Detergents
Wetting
Intermolecular Forces
Nanoparticles and Nanotechnology
Molecular Formula
2-Dimensional Structural Formula
Condensed (semi-structural) formula
Skeletal Formula
Introduction to Functional Groups
Carboxylic Acids


Suggested Study Questions

1. A typical soap molecule, sodium stearate is shown below:
   
   • Draw the full 2-dimensional structural formula for this molecule
   • Write the condensed (semi-structural) formula for this molecule
   • Write the molecular formula for this molecule
2. Draw the skeletal formula for potassium stearate:
   • draw a ring around the functional group
   • name the functional group
   • describe the non-polar part of the molecule
   • describe the polar part of the molecule
3. Draw a structural formula for stearic acid.
4. Write a chemical equation for the neutralisation of stearic acid using sodium hydroxide in aqueous solution.
5. Describe how soap removes dirt during washing.
6. Sodium dodecyl sulfate shown below is a common surfactant molecule found in detergents
   
• Draw the full 2-dimensional structural formula for this molecule
• Write the condensed (semi-structural) formula for this molecule
• Write the molecular formula for this molecule
7. Draw the skeletal formula for potassium dodecyl sulfate:
   • draw a ring around the functional group
   • name the functional group
   • describe the non-polar part of the molecule
   • describe the polar part of the molecule
8. Explain why sodium dodecyl sulfate is classified as an anionic detergent.
9. Compare molecules of sodium dodecyl sulfate and sodium stearate
   • Desribe any similarities between the two molecules
   • Describe any differences between the two molecules
   • Explain how both molecules can be used to remove dirt during washing
10. Consider the problem of detergent sticking to the inside walls of the plastic bottle.
    • Describe the physical properties of the plastic bottle that enable this to happen
    • Use a diagram to help explain why the detergent molecules can "stick" to the plastic bottle
    • Use a diagram to explain why adding water to the not-quite-empty plastic bottle allows more of the detergent to be removed

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Candle-lit Chemistry

What could be more romantic than a candle-lit dinner for two?

Good food, cosy conversation, and the gentle, flickering flames bathing everything in a warm glow.

And all this romance is delivered by the burning of a humble candle, a simple device made up of a block of solid fuel and a wick....

Learn more about the chemistry of candle light in the June 2016 edition of AUS-e-NEWS

You can subscribe to our free newsletter at: http://www.ausetute.com.au/contact.html

Blood Alcohol Concentration

Drinking alcohol impairs your driving ability, so legal limits are set, not for the amount of alcohol you consume, but on the effects of alcohol in your system. In Australia we measure the amount of alcohol in your blood (BAC or Blood Alcohol Concentration) and have set a "maximum legal limit" of 0.05% for most drivers (BAC for learner, provisional and professional drivers is less).
A Blood Alcohol Concentration, BAC, of 0.05% is a weight per volume percentage, w/v%, that is, a BAC of 0.05% is 0.05 grams of alcohol in every 100 mL of blood.
Your Blood Alcohol Concentration, BAC, is effected by the alcoholic beverages you consume. The concentration of alcohol varies between different types of alcoholic beverages, and is given as w/v% concentration as shown in the table below:

Alcoholic Beverage	Typical Alcohol Concentration
light beer	2.7%
ordinary beer	4.9%
wine	12%
spirits	40%
port or sherry	20%

So drinking 100 mL of wine will increase your blood alcohol concentration more than drinking 100 mL of beer.

But drinking alcoholic beverages is not the only way that alcohol can enter your blood stream. Alcohol is also present as an ingredient in other things you might ingest such as in some mouthwashes where it is used for its anti-bacterial properties, for example, original formula Listerine mouthwash contains 26.9% alcohol. Alcohol is also found as the solvent in many over-the-counter and prescription medications, for example, Benedryl has an alcohol concentration of 14% while Benedryl Decongestant has an alcohol concentration of 5%.

The amount of alcohol you ingest will be one factor in determining your blood alcohol concentration, but another factor is the rate at which your body removes alcohol from your blood, and this differs between individuals. There is no way to determine your blood alcohol concentration short of chemical analysis. Since it is not practical for every driver to do this before they set off, guidelines are produced based on the number of "standard drinks" that an "average person" can consume in an hour before he will be "over the legal limit". It should be noted that some people will need to drink less than the guidelines while there are some people who can consume more.
In Australia, a "standard drink" is one containing 10 g of alcohol.
So, in order for you estimate the number of "standard drinks" you have ingested, you need to know the alcohol concentration in your drink and the volume of the drink you drank. Which is not something you are likely to do while standing at the bar ordering your drink!
For this reason, Government authorities issue the guidelines showing the "standard drink" as volumes of different types of alcoholic beverages:

Alcoholic Beverage	Typical Alcohol Concentration	Standard Drink
light beer	2.7%	1 schooner, 425 mL
ordinary beer	4.9%	1 middy, 285 mL
wine	12%	1 glass, 100 mL
spirits	40%	1 nip, 30 mL
port or sherry	20%	1 glass, 60 mL

In order to maintain a blood alcohol concentration under 0.05%, an "average" person can consume 2 standard drinks in the first hour, followed by 1 drink each following hour. If your legal limit is 0.02%, then even just 1 drink can put you over the legal BAC for driving! And, ofcourse, if your "legal limit" is 0%, you cannot ingest any alcohol at all before driving. Be aware that an average person takes about 1 hour to remove the alcohol in 1 standard drink from their blood stream, so it is quite possible for you to be over the "legal limit" hours after you begin drinking!

Further Reading:
Weight/Volume Percentage Calculations: http://www.ausetute.com.au/wtvol.html
Molarity (mol L^-1 concentration) : http://www.ausetute.com.au/concsols.html

Suggested Study Questions:

1. Determine the mass of alcohol in 100 mL of each of the following drinks:
   • light beer
   • ordinary beer
   • wine
   • spririts
   • port
2. Determine the mass of alcohol in 250 mL of each of the following drinks:
   • light beer
   • ordinary beer
   • wine
   • spririts
   • port
3. Calculate the mass of alcohol present in:
   • 425 mL of light beer
   • 285 mL of ordinary beer
   • 100 mL of wine
   • 30 mL spririts
   • 60 mL port
4. Assuming the recommended dose of Benedryl, or Benedryl Decongestant, is 20 mL, what mass of alcohol is present in each dose?
5. How much of each cough mixture above do you need to consume in order to ingest the same amount of alcohol as present in a standard drink?
6. Explain why the volume of a "standard drink" differs for different types of alcoholic beverage.
7. In one hour, Phyl the Physicist drinks 1 schooner of ordinary beer and 1 glass of wine at Science Expo.
   • What mass of alcohol has Phyl consumed?
   • How many "standard drinks" has Phyl consumed?
8. Also at the Science Expo is Bobby the Biologist who mixes herself a Manhattan; 1 nip of vermouth and 2 nips of whiskey, and a dash of bitters, served in a chilled glass with ice and a cherry garnish.
• What is the minimum mass of alcohol Bobby will consume when she drinks this?
• Approximately how many standard drinks is this equivalent to?
9. Sam the Science student has a cold. She takes a 20 mL dose of Bendryl before going to the Expo. In the same hour, Sam drinks 1 middy of light beer at the Expo.
   • What mass of alcohol has Sam consumed?
   • How many "standard drinks" has Sam consumed?
10. Chris the Chemist is the "designated driver" for his team members at the Science Expo. So Chris drinks a 100 mL cup of mulled wine, which is red wine that has been heated with various spices. Chris thinks the alcohol content of his drink must be less than that of 1 "standard drink". Do you agree? Explain your answer.
11. Assuming "alcohol" refers only to ethanol (ethyl alcohol), convert the following concentrations in w/v% to concentrations of ethanol in mol L^-1 (molarity):
    • light beer 2.7%
    • ordinary beer 4.9%
    • wine 12%
    • spririts 40%
    • port 20%
12. Ethanol is a liquid at room temperature and pressure. Why do you think alcohol concentrations are given in units of grams per 100 mL? Explain your answer

Vanadium Phosphate Catalyst

Methane, CH₄, in natural gas can be used as a raw material to produce bromomethane, CH₃Br. Bromomethane (methyl bromide) can then be used in the chemical industry to produce fuels, chemicals, polymers and pharmaceuticals. When  bromomethane is converted into fuels and other chemicals, bromine is released in the form of hydrogen bromide, HBr. Using oxygen and a suitable catalyst, bromine from the hydrogen bromide by-product is embedded back into bromomethane so that no bromine is lost from the system.
Researchers at ETH, Zurich, have identified vanadium phosphate as an ideal catalyst for this reaction.
Vanadium(III) phosphate (vanadium(3+) phosphate), has the structure shown below:

It is a relatively mild oxidising catalyst.
It is a strong enough oxidising catalyst to allow hydrogen bromide to react with oxygen at the surface of the catalyst, but, it is not strong enough to oxidise the methane and brominated reaction products.
It is therefore possible to brominate methane in a single step at atmospheric pressure and at a temperature below 500°C.  The catalyst is also stable, able to resist the corrosive reaction environment.
This makes it an attractive catalyst for this important, industrial, chemical reaction.

Reference:
Vladimir Paunović, Guido Zichittella, Maximilian Moser, Amol P. Amrute, Javier Pérez-Ramírez. Catalyst design for natural-gas upgrading through oxybromination chemistry. Nature Chemistry, 2016; DOI:10.1038/nchem.2522

Further Reading:
Lewis Structures (electron dot diagrams): http://www.ausetute.com.au/lewisstr.html
2-Dimensional Structural Formula: http://www.ausetute.com.au/structural2D.html
Molecular Formula: http://www.ausetute.com.au/molecularformula.html
Halogenation of Hydrocarbons: http://www.ausetute.com.au/halogalk.html
Energy Profiles: http://www.ausetute.com.au/enerprof.html
Reaction Rates: http://www.ausetute.com.au/reactrate.html
Redox Reaction Concepts: http://www.ausetute.com.au/redoxreactions.html

Suggested Study Questions:

1. Draw the Lewis Structures (electron dot diagrams) for each of the following molecules:
   • methane
   • bromomethane
   • hydrogen bromide
2. Draw the 2-dimensional structural formula for each of the following molecules:
   • methane
   • bromomethane
   • hydrogen bromide
3. Give the molecular formula for each of the following molecules:
   • methane
   • bromomethane
   • hydrogen bromide
4. Write a chemical equation to represent the reaction between methane and bromine to produce bromomethane
5. Name the type of reaction given in question 4.
6. Give the reaction conditions necessary for this reaction in question 5 to occur at room temperature and pressure in your laboratory.
7. Why do you think a catalyst is required for this reaction above in order to produce commercial quantities of bromomethane?
8. Which organic compound, methane or bromomethane, do you expect to be the most chemically reactive? Explain your answer.
9. What is meant by the term "oxidising agent"?
10. Is the bromination of methane using bromine a redox reaction? Explain your answer.
11. Refer to the structure of vanadium(III) phosphate given in the article. Give the oxidation state (oxidation number) for each of the following:
    • vanadium
    • oxygen
    • phosphorus
12. Why do you think vanadium phosphate is talked about as being an "oxidising catalyst" rather than as an "oxidising agent"? Explain your answer.

Nanomaterials Monitoring Reactions

Syracuse University Chemists have designed a nanomaterial that changes colour when it interacts with ions and other small molecules during a chemical reaction which enables them to monitor the progress of chemical reactions qualitatively with the naked eye and quantitatively using simple instruments.

Many chemical reactions that occur in aqueous solution involve colourless species. In order to determine how fast the chemical reaction occurs,  Chemists have traditionally tried to "freeze" the reaction at certain points, purify the solution and determine the amounts of unreacted reactants and products produced present at each stage.
Syracuse University Chemists have taken a different route. They are using nanoparticles that react with the byproduct of a reaction. The nanoparticles they used are known as perovskites.
Perovskites are typically composed of metal ions and oxygen. The structure shown below is for a typical perovskite, calcium titanium oxide (CaTiO₃):

Each pale-blue titanium atom is surrounded by 6 red oxygen atoms. The darker-blue calcium atom occupies the space between titanium oxide octahedrons.
The perovskites the researchers used were a bit different to the one shown above. Metal ions were surrounded by halide ions rather than oxygen.
At the nanolevel, perovskites are photo-luminescent, that is, they emit light when "excited" by a laser or a lamp. The colour they emit is largely determined by the concentration of their ions in solution., and it is this property which the researchers used to monitor chemical reactions. It is also this property which is being in exploited in research into light emitting diodes (LEDs), lasers, photodetectors and solar cells.

In this study, perovskites were used to monitor an elimination reaction in which haloalkanes react to form alkenes, eliminating halide ions in the process.
At the start of the reaction, the perovskite fluoresces red.
As the reaction proceeds, halide ions are released which are absorbed by the perovskite nanoparticles, and the fluorescence colour changes from red to yellow to green.
When the fluorescence colour is green, the reaction is over.
The image on the right shows a control colour on the left, and on the right, the changing fluorescence colour of the reaction as it proceeds from 0 minutes at the top to 90 minutes at the bottom.

This technology is patent-pending at the University. In the words of Matthew Maye, Associate Professor of Chemistry, "Who knows, maybe in the future, every chemist will use a Syracuse-based perovskite for monitoring their reactions."

Reference:
Tennyson L. Doane, Kayla L. Ryan, Laxmikant Pathade, Kevin J. Cruz, Huidong Zang, Mircea Cotlet, Mathew M. Maye. Using Perovskite Nanoparticles as Halide Reservoirs in Catalysis and as Spectrochemical Probes of Ions in Solution. ACS Nano, 2016; DOI: 10.1021/acsnano.6b00806

Further Reading:
Nanotechnology: http://www.ausetute.com.au/nanotech.html
Reaction Rate: http://www.ausetute.com.au/reactrate.html
Ligands and Complex Ions: http://www.ausetute.com.au/ligands.html
Naming Haloalkanes: http://www.ausetute.com.au/namhaloa.html
Naming Alkenes: http://www.ausetute.com.au/namsenes.html
Substitution Reactions of Haloalkanes: http://www.ausetute.com.au/rxreacts.html
Dehydration of Alkanols: http://www.ausetute.com.au/dehydraol.html

Suggested Study Questions:

1. Explain the terms "qualitative" and  "quantitative".
2. Explain the term "reaction rate".
3. Explain the term "nanoparticle".
4. What property of nano-perovskite is being applied by the researchers in this article, and how does this property differ for bulk perovskite?
5. Explain how these perovskites can be used to monitor the reaction qualitatively.
6. Explain how you could use these perovskites to monitor the reaction quantitatively.
7. Discuss the differences between ethane, ethene (ethylene) and bromoethane.
8. Consider ethane and ethene (ethylene), which is likely to be more chemically reactive? Explain your answer.
9. Consider ethane and bromoethane. Which is likely to be more chemically reactive? Explain your answer.
10. Explain what is meant by the term "elimination reaction" as used in the article above.
11. What is the difference between and addition reaction, a substitution reaction and an elimination reaction? Give examples of each type of reaction.
12. Write a chemical reaction to represent the elimination of bromide ions from a bromoethane to produce ethene (ethylene). 
13. Consider the structure of CaTiO₃ given in the article. What is the name of the ligand?
14. Give the formula for the perovskite in which all the oxygen atoms have been replaced with bromine.
15. Could the same perovskite be used to monitor a chemical reaction in which water is eliminated from an alkanol to produce an alkene? Explain your answer.

Stinky Socks and Shmelly Shirts?

Northumbria University researchers have identified six volatile organic compounds on dirty socks and t-shirts which are responsible for the stench of your dirty laundry. Surprisingly, some of these compounds can survive washing in a machine with detergent at 20°C, that is, washing in cold water will not remove all the compounds responsible for the smell.

The researchers wanted to identify the volatile organic compounds from dirty clothes before washing, after washing while still wet, and after drying, to see which compounds are responsible for bad smells and to see if they were eliminated during the washing process.

6 men and 2 women were each given a new pair of socks. Each person was asked to wash their feet and dry them before wearing the socks for at least 10 hours in a specified type of shoe. Each sock was then placed in a separate bag and stored in the dark overnight. 9 men were each given a t-shirt to wear for 2-3 hours while taking part in a soccer match. After the match the t-shirts were bagged separately and refrigerated.

The researchers smelled each item and graded it on a scale of 0 (no bad smell) to 10 (very bad smell).
Then the items were washed in a Tergotometer, a lab machine made up of several miniature washing machines, at 20°C using non-perfumed detergent. Each item was graded for odour after washing while still wet and then again after drying.

Using analytical techniques like gas chromatography, the team identified 6 main volatile organic compounds that contribute to the smell of dirty laundry:

• butanoic acid (butyric acid); rancid butter odour
• dimethyl disulfide; onion-like odour
• dimethyl trisulfide; powerful, unpleasant odour
• heptan-2-one (2-heptanone); fruity odour like bananas
• nonan-2-one (2-nonanone); herbaceous odour
• octan-2-one (2-octanone); apple-like odour

As the concentration of these volatile organic compounds decreased after each washing, the items became less smelly.


Reference:
Chamila J. Denawaka, Ian A. Fowlis, John R. Dean. Source, impact and removal of malodour from soiled clothing. Journal of Chromatography A, 2016; 1438: 216 DOI:10.1016/j.chroma.2016.02.037

Further Reading:
Scientific Method: http://www.ausetute.com.au/scientificm.html
Experimental Design: http://www.ausetute.com.au/experimentd.html
Writing Lab Reports: http://www.ausetute.com.au/labreport.html
Introduction to Functional Groups: http://www.ausetute.com.au/fungroup.html
Naming Alkanoic Acids: http://www.ausetute.com.au/namalkacid.html
Naming Alkanones: http://www.ausetute.com.au/namalkanone.html
2-Dimensional Structural Formula: http://www.ausetute.com.au/structural2D.html
Condensed Structural Formula: http://www.ausetute.com.au/condensedsf.html
Molecular Formula: http://www.ausetute.com.au/molecularformula.html
Molar Mass Calculations: http://www.ausetute.com.au/moledefs.html
Gas Chromatography (GC) : http://www.ausetute.com.au/gc.html

Suggested Study Questions:

1. What hypothesis was being tested by the researchers in this experiment?
2. Write an aim for the experiment conducted by the researchers.
3. Write a method for this experiment as a series of steps.
4. Tabulate the results of this experiment.
5. Write a suitable conclusion for this experiment.
6. Discuss how you could improve this experiment.
7. Give the 2-dimensional structural formula for each of the following compounds:
• butanoic acid
• heptan-2-one (2-heptanone)
• nonan-2-one (2-nonanone)
• octan-2-one (2-octanone)
8. On each structural formula above, circle the functional group and name it.
9. Classify each of the compounds listed in question 1 on the basis of their functional groups.
10. Give the molecular formula for each of the following compounds:
    • butanoic acid
    • heptan-2-one (2-heptanone)
    • nonan-2-one (2-nonanone)
    • octan-2-one (2-octanone)
11. Give the condensed structural formula for each of the following compounds:
    • butanoic acid
    • heptan-2-one (2-heptanone)
    • nonan-2-one (2-nonanone)
    • octan-2-one (2-octanone)
12. Calculate the molar mass for each of the following compounds:
• butanoic acid
• heptan-2-one (2-heptanone)
• nonan-2-one (2-nonanone)
• octan-2-one (2-octanone)
13. Which of the following do you think would have the longest gas chromatography retention time ? Explain your answer.
    • heptan-2-one (2-heptanone)
    • nonan-2-one (2-nonanone)
    • octan-2-one (2-octanone)
14. Why is gas chromatography (GC) a good choice of analytical technique for this experiment compared to other chromatographic techniques?

Nano-zinc oxide and the Environment

Increasingly, we are making use of nanoparticles because of their unique properties compared to the same substance in bulk material. Many cosmetics, including sunscreens and sunblocks, now contain nanoparticles. When you go swimming or wash, these nanoparticles are washed off. Depending on where the nanoparticles are washed off, the waste water may directly enter a natural water system such as a river or ocean, it may end up in sewerage sludge, and it may eventually end up on land. What scientists do not know is just how many nanoparticles are entering the earth, air and water.

It is estimated that carbon nanotubes, which form part of a composite material in objects such as bicycle frames and tennis rackets, can take 10 years to breakdown and be released into the environment. On the other hand, about half of the cosmetic nanoparticles enter our waste water within one year.

Europe currently produces about 39,000 tons of nano-titanium dioxide per year, and it is estimated that the concentration of these nanoparticles in effected areas is now 61 micrograms per kilogram of ground. For humans, the maximum "safe" levels for exposure to these nanoparticles is set at:

• 2,500 mg/kg/day for oral exposure
• 2.4 mg/m³ for inhalation

While small amounts of zinc oxide are beneficial to plant growth, larger amounts can impair seed germination. Plants take up the free zinc ions in aqueous solution rather than the zinc oxide particles. This zinc becomes incorporated into the plants we eat. Zinc is an essential element in the human diet. The recommended dietary allowance of zinc for men is 11 mg/day, and for women is 8 mg/day. There are concerns that the increasing level of zinc in  plants may lead to accumulation of zinc in humans which will be detrimental to our health. Ingesting more than about 100 mg of zinc per day may lead to chronic toxicity.

Research into the environmental impact of nanoparticles, and their impact on plant and animal health, will continue for a long time.

Reference:
https://www.sciencedaily.com/releases/2016/05/160512084646.htm

Further reading
Nanotechnology: http://www.ausetute.com.au/nanotech.html
Graphene and Fullerenes: http://www.ausetute.com.au/graphene.html
Solutions Concepts: http://www.ausetute.com.au/solutions.html
Weight percent (w/w): http://www.ausetute.com.au/weightpc.html
Parts per MIllion (ppm): http://www.ausetute.com.au/partspm.html

Suggested Study Questions:

1. What is meant by the term "nanoparticle"?
2. If a nanoparticle of zinc oxide has a diameter of 20 nm, what is its diameter in:
   • metres
   • centimetres
   • millimetres
   • micrometres
3. Give an example of one property of bulk zinc oxide that is different to nanoparticles of zinc oxide.
4. Explain why zinc oxide nanoparticles are used in sunscreens.
5. What is a carbon nanotube?
6. Why are carbon nanotubes used in the production of bicycle frames?
7. Why are concentrations of titanium dioxide nanoparticles in soil given in units of micorgrams per kilogram of soil rather than in moles per litre?
8. Convert the following concentrations into parts per million (ppm)
   • 2,500 mg kg^-1
   • 2.4 mg m^-3
9. Using the recommended dietary allowance figures in the article, determine the mass in grams of zinc allowed for a:
   • 58 kg woman each day
   • 79 kg man each day
10. A typical vitamin pill contains 25 mg of zinc. By consuming 1 tablet per day, will the man or woman above exceed the recommended daily allowance of zinc?
11. 6 raw oysters contain 32 mg of zinc. How many oysters can the man and woman above eat before exceeding the recommended dietary allowance of zinc?
12. 85 g of cooked beef contains 7 mg of zinc. What mass of beef can the man and woman above ingest before exceeding the recommended dietary allowance of zinc.
13. 28 g of dry roasted cashews contain 1.6 mg of zinc. What mass of zinc, in grams, is present in 750 g bag of cashews?
14. 1/2 cup of cooked red kidney beans contain 0.9 mg of zinc. How many cups of red kidney beans would our man and woman above need to consume in order to achieve their recomended dietary allowance of zinc?
15. Do you think you should take a daily vitamin pill containing zinc? Justify your answer.