How to Kill the COVID-19 Virus

By the middle of 2020 millions of people had been infected with a virus which causes a disease known as COVID-19 and hundreds of thousands of people had died.

So I was intrigued when I read that Professor Mary-Louise McLaws, an infection control expert from the University of New South Wales, had stated that, "it's relatively easy to kill compared to some other viruses".

Why is the COVID-19 virus easy to kill and how do you kill it? 

Read this edition of AUS-e-NEWS to find out more.

Subscribe to AUS-e-NEWS at https://www.ausetute.com.au/ausenews.html

Micellar Water

Once upon a time you would buy a bar of soap and use it to wash your hands, face, body, and possibly even your hair.
Not today! Now you have hand-wash for your hands, body-wash for your body, shampoo for your hair, and a huge range of different products to clean your face including "micellar water" or "micellar cleansing water".
Unlike other face-cleaning products which need to be washed off with water, the makers of "micellar water" claim that it will cleanse your skin without vigorous rubbing or rinsing.
Intriguing! This "micellar water" sounds like some kind of magic doesn't it?
What's in "micellar water" and how does it work?

Read all about it in the September 2019 edition of AUS-e-NEWS, AUS-e-TUTE's free quarterly newsletter for chemistry students and teachers.

Want to subscribe to AUS-e-NEWS?

Go to https://www.ausetute.com.au/ausenews.html

Betaines

Betaines are found in plants, animals and microorganisms. Rich sources of betaines in the human diet are seafood, spinach and wheat germ or bran. Research is beginning to indicate that betaines are important nutrients for the prevention of chronic disease. Researchers are also interested in incorporating betaines into polymer brushes used for antifouling and lubrication.

Betaines are compounds with a positively charged functional group linked to a negatively charged functional group with an alkyl chain in between. The alkyl chain is often referred to as an alkyl chain spacer.  The general structure of an N-alkyl betaine is shown below:

The first betaine discovered was found in sugar beets in the nineteenth century. This betaine is (trimethylammonio)acetate, also known as trimethylglycine, and its skeletal structure is shown below:

Another example of a betaine is 2-(trimethylammonio)octadecanoate (also known as hexadecylbetaine) with the skeletal structure shown below:

2-(Trimethylammonio)tetradecanoate, or dodecylbutaine or laurylbutaine, is also a butaine and its skeletal structure is shown below:

Betaines are strongly attracted to water molecules because of these two charged functional groups.
The solubility of betaines in water is dependent on the length of the carbon chain, as well as on temperature and pH. 
In acidic solution, betaines acquire a net positive charge and act like a cationic surfactant. In anionic solutions, betaines acquire a net negative charge and act like an anionic surfactant.

Betaines can also be used in polymer brushes which are polymers bound to a surface. Polymer brushes can be used for antifouling and lubrication because the hydration of the ionic groups reduces the ability of other materials to adhere to the surface. 

Researchers at Kyushu University recently investigated a series of alkly chain spacers of different lengths bound to a silicon surface. They found that the polymer brushes swelled in humid air and water. It is believed that this is due to electrostatic repulsion between charged groups, and not dependent on the length of the alkyl chain.
In deionised water, net positive cations and net negative anions are repelled because of the  electrostatic force which causes the chain dimension to expand, whereas they shrink under high ionic strength by a charge screening effect of the bound ions.

Reference:
https://www.sciencedaily.com/releases/2017/08/170821094302.htm

Further Reading
Introduction to Functional Groups
2-Dimensional Structural Formula
Condensed Structural Formula
Molecular Formula
Amino Acids
Surfactants ( as found in synthetic detergents)
Intermolecular Forces and Solubility

Suggested Study Questions

1. Locate and identify each functional group on the skeletal structural formula of
• general formula N-alkyl betaine 
• (trimethylammonio)acetate
• 2-(trimethylammonio)octadecanoate
• 2-(trimethylammonio)tetradecanoate
2. Draw a 2-dimensional structural formula for each of the following molecules:
• (trimethylammonio)acetate
• 2-(trimethylammonio)octadecanoate
• 2-(trimethylammonio)tetradecanoate
3. Write the condensed structural formula for each of the following molecules:
• (trimethylammonio)acetate
• 2-(trimethylammonio)octadecanoate
• 2-(trimethylammonio)tetradecanoate
4. Write the molecular formula for each of the following molecules:
• (trimethylammonio)acetate
• 2-(trimethylammonio)octadecanoate
• 2-(trimethylammonio)tetradecanoate
5. Compare the structure of betaines to that of 2-amino acids. Can N-alkyl betaines be classified as alpha amino acids (2-amino acids) ? Justify your answer.
6. Write chemical equations to describe what happens to an N-alkyl betaine in:
• acidic aqueous solution
• basic aqueous solution
7. Compare the structure of N-alkyl betaines to the surfactants found in synthetic detergents. In what ways are surfactant molecules 
• similar to N-alkyl betaines
• different from N-alkyl betaines
8. Explain how N-alkyl betaines act like 
• a cationic surfactant in acidic aqueous solution
• an anionic surfactant in basic aqueous solution
9. Consider the structure of (trimethylammonio)acetate and 2-(trimethylammonio)octadecanoate. Which molecule do you expect to be more soluble in water? Justify your answer.
10. Consider the structure of (trimethylammonio)acetate and 2-(trimethylammonio)octadecanoate. Which molecule do you expect to be more soluble in paraffin oil? Justify your answer.

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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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?

DOSS and Oil Spills

The molecular formula for dioctyl sodium sulfosuccinate, DOSS, is shown on the right. This is the anionic detergent molecule that was used to disperse the oil from the Deepwater Horizon spill in the Gulf of Mexico in 2010. When applied to an oil spill, DOSS decreases the size of oil droplete and prevents large oil slicks from forming.
BP applied about 1.84 million gallons of DOSS to the 210 million gallons of oil that is estimated to have gushed out of the oil well.
At the time it was believed that DOSS degraded rapidly in the environment so that it would not harm the marine environment.

Recent studies, however,  have shown that DOSS persists in the environment for much longer than was previously thought. Four years after the Gulf oil spill, DOSS remains present in deep-sea sediments and corals and in sand patties on Gulf beaches. mean for marine life or for the people who frequent the beaches? Scientists do not yet know what this might mean for marine life or for the people who frequent the beaches so some Gulf beaches have signs to warn people not to touch the sand patties.

Reference:
Helen K. White, Shelby L. Lyons, Sarah J. Harrison, David M. Findley, Yina Liu, Elizabeth B. Kujawinski. Long-Term Persistence of Dispersants following the Deepwater Horizon Oil Spill. Environmental Science & Technology Letters, 2014; 1 (7): 295 DOI: 10.1021/ez500168r

Further Reading:
http://www.ausetute.com.au/members/detergent.html (detergent tutorial for members)
http://www.ausetute.com.au/members/soaps.html (soaps tutorial for members)
http://www.ausetute.com.au/members/molecularformula.html (molecular formula tutorial for members)
http://www.ausetute.com.au/members/structural2D.html  (2-dimensional structural formula tutorial for members)
http://www.ausetute.com.au/members/condensedsf.html (Condensed structural formula tutorial for members)
http://www.ausetute.com.au/members/skeletal.html (Skeletal formula tutorial for members) 

Suggested Study Questions:

1.  Explain why dioctyl sodium sulfosuccinate, DOSS, is an anionic detergent molecule.
2. Give the name for the type of formula shown for dioctyl sodium sulfosuccinate, DOSS, in the article
3. Identify the functional groups found on a dioctyl sodium sulfosuccinate, DOSS, molecule.
4. Identify areas of the dioctyl sodium sulfosuccinate, DOSS, molecule that are:
   • hydrophilic
   • hydrophobic
5. Explain how the dioctyl sodium sulfosuccinate, DOSS, molecule might dissolve in water.
6. Explain how the dioctyl sodium sulfosuccinate, DOSS, molecule might dissolve in oil.
7. Explain how dioctyl sodium sulfosuccinate, DOSS, molecules might help break an oil spoil up into smaller oil droplets.
8. Write a complete 2-dimensional structural formula for dioctyl sodium sulfosuccinate, DOSS.
9. Write a condensed structural formula for dioctyl sodium sulfosuccinate, DOSS.
10. Write the molecular formula for dioctyl sodium sulfosuccinate, DOSS.

Capillary Action

Why does cola rise up a drinking straw?
Why does water creep up paper?
Why does a tee-shirt "soak up" sweat?

AUS-e-TUTE has a new set of Surface Chemistry resources for Capillary Action (also known as capillarity, capillary motion, or, wicking). AUS-e-TUTE Members can log-in to use the new tutorial, game, test.

Not an AUS-e-TUTE Member?
Find out what you're missing at http://www.ausetute.com.au/membership.html
and register for membership at http://www.ausetute.com.au/register.html
There is a free sample tutorial on capillarity currently available at
http://ww.ausetute.com.au/capillarity.html

Keeping Glass Clear

Windows get "foggy" when water condenses on them. The glass of the window is colder than the surrounding air, and the air contains moisture which is gaseous water. When the gaseous water hits the surface of the cooler glass, the water turns into a liquid.
What happens next depends on the nature of the glass surface.

If the glass were perfectly flat, and perfectly clean, the strong adhesion between the water molecules and the hydrophilic glass would allow the water to spread out evenly over the surface of the glass so you would still be able to see through the glass.
If the glass is dirty it has an uneven cover of hydrophobic particles which reduces the adhesive forces between the water and the surface resulting in a multitude of small water droplets collecting on the surface which means it is harder to see through the glass.

Traditional ways of keeping the glass of car windows "fog free" include wiping the water off if it is on the outside, or turning on the heater or air-conditioner to increase the rate of evaporation if the "fog" is on the inside of the car.

From a chemistry point of view, we can see there are two possible approaches to making a coating for the glass surface so that it will stay "fog free":

• Make an extremely hydrophobic, transparent coating, then any water that comes into contact with the surface will not adhere at all and will just run off. This is the traditional approach used to create water repellent coatings and materials.
• Make an extremely hydrophilic, transparent coating so that any water than comes into contact with the surface will spread out evenly, making an extremely thin, transparent, layer over the surface. This is what scientists at A*STAR's Institute of Materials Research and Engineering (IMRE) have done. They have created a new technology, CleanClear, which is a durable and permanent ceramic coating that is transparent and superhydrophilic, which means it attracts water instead of repelling it.

The new transparent, superhydrophilic ceramic coating is anticipated to have many application; on car windows, glass cooking pot covers, hot food displays, it might even be used to keep your spectacles clear.

Reference:
The Agency for Science, Technology and Research (A*STAR). "Creating a water layer for a clearer view." ScienceDaily. ScienceDaily, 12 June 2014. www.sciencedaily.com/releases/2014/06/140612212430.htm.

Further Reading
http://www.ausetute.com.au/members/surfacetension.html
http://www.ausetute.com.au/members/wetting.html
http://www.ausetute.com.au/members/heatlatent.html

Suggested Study Questions

1. Write a balanced chemical equation to show the condensation of gaseous water on a glass surface.
2. Write a balanced chemical equation to show how liquid water evaporates off a glass surface.
3. Use (kinetic) particle theory of matter to explain what happens when water condenses and evaporates.
4. Define the terms hydrophilic and hydrophobic.
5. Define the terms adhesion and cohesion.
6. Explain why water forms spherical droplets.
7. Explain why glass is a hydrophilic surface.
8. Explain why dirty glass, glass covered with oily particles, is hydrophobic.
9. Explain how a water repellent coating on glass might work.
10. Discuss potential problems with using CleanClear on car windows, that is, what factors might reduce its effectiveness and why.

Wet, Wetting and Wettability

In Surface Chemistry, the concept of wetting or wettability is very important. Understanding wetting enables scientists to make water repellant fabrics, or, to make sponges that soak up oil spills, or to produce detergents that remove grease and oil in water.

Learn more about wetting and wettability with AUS-e-TUTE's news tutorial, game and test.
Members should log-in and go to the Surface Chemistry section for links to the new resources.

Not an AUS-e-TUTE Member?
There is a free tutorial available: http://www.ausetute.com.au/wetting.html

Surface Tension

Why are rain drops spheres?
How can you float a steel needle on water?
AUS-e-TUTE has just added new Surface Tension resources.
AUS-e-TUTE members should log-in to use the new tutorial, game, test.

Not an AUS-e-TUTE Member?
There is a free tutorial available: http://www.ausetute.com.au/surfacetension.html

Sticking Non-stick Surfaces Together

Polymers made up of non-polar, or only very slightly polar, functional groups are said to have low surface energy and poor adsorption which means that the surfaces are not "sticky".
Teflon (polytetrafluoroethylene or PTFE) is an example of a polymer with a very low surface energy, so low that it is used to provide non-stick coatings to things like pots and pans.
Silicones (polysiloxanes), with the general formula [R₂SiO]_n in which R is an organic group such as a methyl or ethyl group, also tend to have low surface energies. Because most materials do not adhere to, or stick to, silicones, silicones have become widely used to make flexible "rubber" molds.

So, how do you join together materials like these that are not "sticky"?

This is the question that scientists at Kiel University in Germany have been studying, and the solution they have devised is to use nano-scaled crystal linkers as internal staples. These staples are made of zinc oxide in which the crystals are shaped like tetrapods, that is, each staple has 4 legs. Zinc oxide crystals are sprinkled evenly onto a heated layer of teflon. Then a layer of silicone is poured on top. The material is then heated to 100^oC for less than an hour in order to join the materials firmly together.When the zinc oxide crystals are heated, the tetrapods pierce the teflon and silicone materials, sink into them and get anchored.
Peeling the teflon layer off the silicone layer held together by the tetrapod staples is about the same as peeling sticky tape off glass.

Reference:
X. Jin, J. Strueben, L. Heepe, A. Kovalev, Y.K. Mishra, R. Adelung, S.N. Gorb, A. Staubitz. Joining the un-joinable: Adhesion between low surface energy polymers using tetrapodal ZnO linkers. Advances Materials, 2012 DOI: 10.1002/adma201201780

Further Reading
Polymers and Polymerization
Functional Groups
Molecule Polarity

Suggested Study Questions:

1. Define the term polymer
2. Give two examples of polymers that are commonly used in households.
3. Define the term functional group and give three exaples.
4. Explain what is meant by a polar functional group and a non-polar functional group.
5. Give the structural formula for the monomer that can be used to form teflon.
6. Are the bonds in the monomer you have drawn in question 5 polar or non-polar bonds. Explain your answer.
7. Is the molecule that is the monomer in question 5 polar or non-polar. Explain your answer.
8. Given the general formula for silicones provided in the article, write the formula for:
   • polydimethylsiloxane
   • polydiethylsiloxane
9. Give a possible structural formula for the monomer used to produce each of the silicone polymers in question 8.

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
     
   
   

Replacing Phosphates in Detergents

From the Sydney Morning Herald (Australia) July 17, 2011, "IN THE latest round of supermarket ''me-too-ism'', Coles and Woolworths have backed a plan to rid shelves of environmentally damaging detergents.

The supermarkets have pledged to make their home brand laundry detergents phosphate-free by next year, a year ahead of a pledge this month by discount supermarket chain Aldi to ban the chemicals, which have been linked with damage to waterways and marine life."

Sodium phosphates have often been added to detergents as a builder, or water softener. Builders are chemical compounds that remove calcium ions from solution by complexation or precipitation.

The sodium phosphates that have been used as builders include orthophosphates and complex phosphates:

1. Orthophosphates which precipitate out metallic ions such as calcium:
• trisodium phosphate, Na₃PO₄
• disodium phosphate, Na₂PO₄
2. Complex phosphates which produce metallic complexes with metallic ions that do not necessarily precipitate out of solution:
   
• tetrasodium pyrophosphate Na₄P₂O₇
• sodium tripolyphosphate (STPP) Na₅P₃O₁₀
• sodium tetraphosphate Na₆P₄O₁₃
• sodium hexametaphosphate (NaPO₃)₆

Sodium tripolyphosphate (STPP), the main detergent phosphate, is something of a wonder ingredient for detergents, helping to maintain pH, remove food and grease, inhibit corrosion, and suspend insoluble dirt. For the consumer, its main visible benefit was to reduce spotting and filming by sequestering calcium and magnesium ions in the wash water.

Sodium phosphates, which can make up to 50% of the weight of a detergent, can lead to problems with eutrophication of lakes and streams, resulting in the growth of algal blooms, killing fish and plants.

On July 1, 2010, major cleaning product manufacturers finished removing phosphates from all home automatic dishwasher detergents sold in the U.S. a result of new laws in 16 states, but consumers living in areas with hard water were not happy with many of the new phosphate-free products. Phosphate alternatives such as zeolites leave residue on dishware while citrates are expensive and don’t work as well.

In order to replace the effectiveness of phosphates, a long list of additives is used which can include:

• sodium citrate which helps maintain the proper pH level of the detergent helps immobilize soils that have been removed during the wash
  
• polyacrylates which are polymers designed to bind with calcium and magnesium ions, allowing the detergent to better perform
  
• tetrasodium etidronate which is also used as a water softening agent
  
• phosphonates which are also a water softening agents, but, although they contain phosphorus, the toxicity of phosphonates to aquatic organisms is low.
  

Reference:

http://www.smh.com.au/environment/conservation/phosphates-are-all-washed-up-20110416-1dijs.html#ixzz1JkEcsejm

Further Reading

Detergents

Naming Ionic Compounds

Writing Ionic Formula

Molecular Mass Calculations

Percentage Composition

Concentration (molarity)

Concentration (ppm)

Study Questions

1. Calculate the molecular mass (formula weight) of each of the following compounds:
• trisodium phosphate, Na₃PO₄
• disodium phosphate, Na₂PO₄
• tetrasodium pyrophosphate Na₄P₂O₇
• sodium tripolyphosphate (STPP) Na₅P₃O₁₀
• sodium tetraphosphate Na₆P₄O₁₃
• sodium hexametaphosphate (NaPO₃)₆
2. Calculate the percent by mass of phosphorus present _{in each of the following compounds:}
   
• trisodium phosphate, Na₃PO₄
• disodium phosphate, Na₂PO₄
• tetrasodium pyrophosphate Na₄P₂O₇
• sodium tripolyphosphate (STPP) Na₅P₃O₁₀
• sodium tetraphosphate Na₆P₄O₁₃
• sodium hexametaphosphate (NaPO₃)₆
3. Write the formula for each of the following
   
• tripotassium phosphate
• dipotassium phosphate
• tetrapotassium pyrophosphate
• potassium tripolyphosphate
• potassium tetraphosphate
• potassium hexametaphosphate
  
4. What do each of the following prefixes mean?
   • di
   • tri
   • tetra
   • hexa
   • poly
   
   
5. Assuming a particular brand of detergent, ABC, contains 35% by mass of sodium tripolyphosphate (STPP) Na₅P₃O_{10, how much phosphorus would be present in 10 grams?}
6. _{If 10g of ABC were placed in a dishwasher which used 60L of water to wash the dishwashers, what would be the concentration of ABC detergent in mol/L?}
7. _{Using the information in question 4, calculate the concentration of phosphorus in the wash water, in parts per million.}
   

Cardanol

Chemists at The City College of New York have designed a molecule which has both water-adhering and water-repelling ends, from cardanol (the structure on the right), a naturally available material found in cashew nutshell liquid.

When mixed with water, the designer molecules formed a self-assembled structure called a micelle with a water-adhering exterior and water-repelling interior.

At 50^oC the micelles take on a 3-dimensional structure known as a vesicle that is about 200 times larger and more viscous. The molecules stick together enough to be draw out into a thin strand, just like glue.

Cooling the material allows the molecules to revert to their original micellar structure.

Heating causes the micelles to re-arrange themselves into an interlocking bi-layer which undergoes curvature. The structure is stabilized in part by the hydrogen bonding.

Reference
Vijai S. Balachandran, Swapnil R. Jadhav, Padmanava Pradhan, Sacha De Carlo, George John. Adhesive Vesicles through Adaptive Response of a Biobased Surfactant. Angewandte Chemie International Edition, 2010; DOI: 10.1002/anie.201005439

Further Reading
Detergents
Soaps and Saponification
Functional Groups
Percentage Composition
Intermolecular Forces
Intramolecular Forces

Study Questions

1. Identify the functional groups present in a molecule of cardanol.
2. Give the molecular formula for cardanol.
3. Calculate the percentage of carbon, hydrogen and oxygen present in a mole of cardanol.
4. On the molecular structure of cardanol, identify the water-adhering area and the water-repelling area.
5. What is the name given to a molecule that adheres to water?
6. What name is given to a molecule the repels water?
7. Draw a diagram to show how cardanol molecules could form a micelle.
8. Given the description of the behaviour of the designer molecule in the article above, in what ways do you think it differs from the structure of cardanol?