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.

Standard Solutions

What is the difference between a primary standard and a secondary standard in volumetric analysis?
What substances can be used as a primary standard?
How do you make a standard solution?

All these questions are answered in AUS-e-TUTE's new tutorial on standard solutions.
Members should log-in and go to the Volumetric Analysis section on the index page, or,
follow the links from your Chemistry syllabus study guide.
Members will also find a game, test and exam as well as tutorial on this topic.
Teachers will find  a worksheet wizard which will let you make, and print off, a worksheet on this topic.

Not an AUS-e-TUTE Member?
There is currently a "free-to-view" tutorial at http://www.ausetute.com.au/titrstand.html

Borospherene

A molecule containing 60 carbon atoms in a cage-like spherical shape was first produced in 1985 and was called buckminsterfullerene, or bucky-ball. The structure is like a soccer ball, made up of 20 hexagons and 12 pentagons.
A bucky-ball is shown on the right. Each blue sphere represents a carbon atom, and each cream-coloured line represents a covalent bond between 2 carbon atoms.
One of the reasons that scientists are very interested in buckminsterfullerene is because of its ability to hold atoms of different elements inside the cage-like structure. This could enable bucky-balls to be used to deliver drugs in the body, or to store atoms such as hydrogen.

In 1991, scientists discovered that carbon atoms can also form nanotubes, and in 2004, sheets of carbon atoms just 1 atom thick known as graphene were discovered.

But can atoms other than carbon make these kinds of 3-dimensional networks at the nanometre level?

Researchers from Brown University, Shanxi University and Tsinghua University in China have shown that a cluster of 40 boron atoms forms a hollow molecular cage similar to a carbon buckyball. It's the first experimental evidence that a boron cage structure does indeed exist.
This boron cage, called borospherene, isn't quite as spherical as its carbon cousin. Rather than a series of five- and six-membered rings formed by carbon, borospherene consists of 48 triangles, 4 seven-sided rings and 2 six-membered rings. Several atoms stick out a bit from the others, making the surface of borospherene somewhat less smooth than a buckyball.

Because of the electron deficiency of boron, borospherene is likely to bond well with hydrogen. So these tiny boron cages could serve as safe houses for hydrogen molecules.

Reference:
Brown University. "Researchers discover boron 'buckyball'." ScienceDaily. ScienceDaily, 13 July 2014. .

Further Reading:
Graphene
Molecular Formula
Allotropes

Suggested Study Questions:

1. Write the molecular formula for buckminsterfullerene given the information in the article above.
2. How many covalent bonds does each carbon atom in buckminsterfullerene make?
3. Do you expect buckminsterfullerene to be soluble or insoluble in water? Explain your answer.
4. Draw a representation of graphene.
5. How many covalent bonds does each carbon atom make in graphene?
6. Do you expect graphene to conduct electricity? Explain your answer.
7. Write the molecular formula for borospherene based on the information provided in the article.
8. In the pictorial representation of borospherene given above, what do each of the following represent:
   • red spheres
   • yellow lines
9. In what ways are the structures of bucky-balls and borospherene similar?
10. In what ways are the structures of bucky-balls and borospherene different?

Dilution Factors

I've always thought that an understanding of dilution factors can make a Chemistry student's life a whole lot easier, but at the same time, always avoided teaching it (or indeed making reference to it) because of the muddle students make of it (thinking that every calculation involving a solution can be dealt with using dilution factor "formulae") .... and even worse, biology students always seem to have a desire to just "add volumes" together (even if the volumes are not additive!).

The new dilution factor resources are available to AUS-e-TUTE Members in the Members Only area (and teachers will find a worksheet wizard in the Teachers Area).

Not a member?
You can find out about AUS-e-TUTE Membership at  http://www.ausetute.com.au/membership.html

and you can join AUS-e-TUTE at http://www.ausetute.com.au/register.html

There is a free-to-view tutorial currently available at http://ausetute.com.au/dfactor.html

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

Problem Solving in Chemistry

Chemistry students are expected to be able to solve chemistry problems.
On every exam paper, there will be an assortment of problems for students to solve.
Sometimes they do it well, sometimes they do it OK, and sometimes they do it badly.
Often, we give students time before exams to practice answering exam questions.
But how often do chemistry teachers actually explicitly teach problem solving skills?
Often we expect students to "follow our lead" when we demonstrate how to solve particular problems, but do we ever give them a good general framework that they could use to solve any problem they are likely to face in exams?
Most likely the answer is no.
"Surely, by the time students get to the senior years of high school they should be able to solve problems right?" I hear you ask.
While this is a reasonable expectation, the reality is that quite a few can't, just try reading the annual examiners reports and you will get a feel for the kinds of difficulties many students face when trying to solve problems.
So, I've spent some time doing some reading, quite a lot of thinking, and more typing than I'd like, in order to produce a framework for problem solving in chemistry.

You can see the results on the AUS-e-TUTE page on Problem Solving in Chemistry:
http://www.ausetute.com.au/stopgops.html

and a results-only demonstration of the problem solving process in action has been added to the bottom of the amended Dilution Calculations page:
http://www.ausetute.com.au/dilucalc.html

The problem solving page might seem like a lot of reading, but once your students become familiar with the process it is really very quick. It helps them identify potential difficulties BEFORE they actually start doing calculations, ensures they answer the question they were asked and that they check the answer to make sure it is reasonable.

If you happen to teach physics and/or maths as well as chemistry, the method can be applied to these subjects as well.

Because acronyms are useful, I've called this the StoPGoPS approach to problem solving, for reasons that will become self-evident when you read the problem solving page, and I've used a set of traffic lights as a visual aid to recall.

Please feel free to comment on the usefulness of this problem solving model.

Trans Fats

Some fats, such as polyunsaturated fats, are thought to be good for us.

They lower the "bad" type of cholesterol which has been linked to heart disease.

Other fats, such as saturated fats and trans fats, are considered to be bad for us because they increase this "bad" type of cholesterol.

Since the beginning of the 21st century, health authorities all over the world have been calling for the elimination of trans fats from commercially produced food products.

But what is a trans fat and where does it come from?

Go to the June 2014 issue of AUS-e-NEWS for the chemistry of Trans Fats.

Haven't received your free newsletter yet?

Email us at 

and we'll email it to you.