Chemistry Blog

Feb 10

How Water Freezes Lower on a Negatively Charged Surface

I first heard this on National Public Radio and then I searched for it. In short, David Ehre, Etay Lavert, Meir Lahav, and Igor Lubomirsky report in Science, (Water Freezes Differently on Positively and Negatively Charged Surfaces of Pyroelectric Materials) water freezes at a lower temperature (-18°C) on the negatively charged side of a lithium tantalate plate with a strontium titanate film than on the positive side (-7°C, and -12°C uncharged).

Is this unique or is this a manifestation of something in our standard introductory organic chemistry textbooks? I thought it was the latter. Let me explain how.

For the purpose of thinking about this problem, let us assume the metal surface is simply a flat charged surface, without contour. If the surface has a negative charge, then the water should be attracted like a flagpole. One hydrogen should be anchored to the surface of the metal at right angles and the other hydrogen could spin about that axis with the flag hydrogen at 105°. It should not be surprising that this configuration should not be as good of a surface as one with greater rigidity.

If we compare with the positively charged surface, then both pairs of non-bonded electrons should be anchored to the surface and locking the hydrogens in a fixed position. This should limit the degrees of freedom and enable crystal growth.

For those that may be wondering where this is found in your textbook, it may not be there. The negatively charged surface is the one that seemingly will have the most important stereochemical constraints and information in a textbook. The analogy I was comparing is the stereochemical restrictions of proton transfer reactions. In that context, the angle between a proton and donor-acceptor electron pairs in a hydrogen bond is usually 180°. One can find smaller bond angles in intramolecular proton transfer reactions, such as the decarboxylation of a beta-ketoacid or a Cope elimination reaction of an amine-oxide as six and five-membered ring examples.

You may also encounter a … transition state which transfers a proton via a four-membered ring. While this mechanism is present in some textbooks, I am troubled by a lack of precedent for this proton transfer. In a normal hydrogen bond, the preferred bond angle is 180°. Variations from 180° are commonly found in six and five-membered rings …

While the four-membered ring is expedient and avoids a zwitterionic intermediate, I am skeptical sufficient experimental data exists to support it. In the normal hydrogen bond, the electron-electron repulsion forces the nuclei to be linear.  While smaller angles are present in six and five-membered rings, a continued decrease in bond angle increases the electron-electron repulsion exponentially as predicted by Coulomb’s Law. This could be compensated for with a large nucleus…. A larger nucleus can attract electrons and mitigate their repulsion. However, I have resisted writing any examples of proton transfers via four-membered ring intermediates. [A Handbook of Organic Chemistry Mechanisms, p 65]

I could have drawn a model with two attachments points for water. That would probably look better if a plane charged surface is present rather than several pairs of electrons. If a two point model were to be present, then another model for the melting point difference is needed.

P.S. this is my first post here. As I often seem to think of something bleeding edge, not obvious, heretical, or downright wrong, I hope if there were any comments, this is just an idea. I may change my mind tomorrow.

Feb 08

Geoengineering Scientists and Congress

(From Left to Right)
Dr. David Keith
Dr. Philip Rasch
Dr. Klaus Lackner
Dr. Robert Jackson

Geoengineering is a wonderful example of taboo science. Most people would fall within 2 camps. Camp 1 considers geoengineering with disdain as it mucks with the natural environment. Camp 2 probably wouldn’t want their government involved in planetary climate control. With those entrenched camps where do scientists fit in?

Scientists were called as witnesses before The House Subcommittee on Energy & Environment last week in regards to geoengineering. The witnesses invited were…

  • Klaus Lackner (Geophysics,
    Earth and Environmental Engineering): Covering CO2 sequestration
  • Robert Jackson (Biology): Covering Biological and Land Strategies to lower CO2
  • Philip Rasch(Atmospheric Science but a chemist by training): Calling for a Manhattan project type approach to researching geoengineering
  • David Keith (Chemical and Petroleum Engineering): Mainly advocating that some sort of global policy towards geoengineering needs to be developed. The most sane and coherent witness; scientists don’t usually fair well before politicians.

So why care about taboo science? The simple matter is that it would cost 1-2 billion a year to return the planet to pre-industrial levels of temperature, assuming they use cheap sulphates to do the job. This means any number of nations, frankly any wealthy cohort of industrialists, can take climate control into their own hands.

Since geoengineering is a delicate subject to broach to the public, transparency is crucial and wasn’t loss on the chairman Brian Baird (D-WA). Congressman Baird mentions how some citizens believe their government is placing psychotropic drugs in jet fuels, the so called chemtrails and remarked “…legitimate scientific research [in geoengineering] must not get tied up in these kind of things.”

However, all the scientists were taken aback by Randy Neugebauer (R-TX), my favorite exchange was the following.

Randy Neugebauer (R-TX)

Randy Neugebauer, “What percent of the atmosphere is CO2?”
Scientist, “390 parts per million”.
Randy Neugebauer, “Less than one tenth of one percent…This tiny minuscule amount…[can’t] be more important factor in our climate than solar activity”.

I’m not even sure where to begin to broach such a deep misunderstanding of climate change. I would have mentioned to Mr. Neugebauer that he would be dead if that minuscule amount of CO2 was removed from the atmosphere, as all plants would die followed by animals in short order. The concept of small amounts having huge impacts in large dynamic systems is an important lesson to teach, even more so to do it dexterously. These types of exchanges went on for some time. I’m left wondering why Randy Neugebauer is even on the Subcommittee on Energy & Environment in the first place.

The ranking Republican, Bob Inglis (R-SC), had this to say in his last remarks, “I believe in a basic role of government is to do basic research, its an important function that we do.” It is nice to know that basic science research is appreciated by both sides, even though there is always a rogue member in every committee.

Press Release: Subcommittee Examines Geoengineering Strategies and Hazards


Feb 04

Chemical Journalism

For those with an interest in journalism and time this summer ACS is offering a summer internship in the C&EN newsroom. Deadline is Feb 22nd.

Chemical & Engineering News, the weekly newsmagazine of the American Chemical Society, seeks an intern for our Science/Technology/Education department for the summer of 2010.

C&EN reports current events in the chemical enterprise, including recent advances in research, education, industry, funding, and regulatory policy. C&EN reaches all 154,000 members of the ACS each week, and its online edition receives more than 13 million page views per year.

The candidate should be a highly motivated student or recent graduate with demonstrated interest in science writing and at least a bachelor’s degree in chemistry or a related field. The intern will have a chance to write bylined news and feature stories for publication in C&EN. We offer a $1500 monthly stipend for three months. The intern ideally will be based in our Washington, DC, headquarters; however, exceptional candidates unable to relocate may be considered. Starting and ending dates are flexible.

Contact Amanda Yarnell for more information about this year’s internship.

Link: C&EN Internships

Update: There is also an associate editor position available.


Feb 02

Good News: Lancet Article Author Cooks Data on Vaccine/Autism Link Updated and Bumped: Lancet Retracts Wakefield’s 1998 Paper

(See important update, below)

The Times of London yesterday ran a story that Jenny McCarthy needs to read (h/t  The article details an investigation of the results of the 1998 paper in the Lancet medical journal which shows a link between thimerosal in MMR vaccines and autism.  The investigation concludes the author, Andrew Wakefield, manipulated data to show the link.

Confidential medical documents and interviews with witnesses have established that Andrew Wakefield manipulated patients’ data, which triggered fears that the MMR triple vaccine to protect against measles, mumps and rubella was linked to the condition.

The research … claimed that the families of eight out of 12 children attending a routine clinic at the hospital had blamed MMR for their autism, and said that problems came on within days of the jab. The team also claimed to have discovered a new inflammatory bowel disease underlying the children’s conditions.

However, our investigation … reveals that: In most of the 12 cases, the children’s ailments as described in The Lancet were different from their hospital and GP records. Although the research paper claimed that problems came on within days of the jab, in only one case did medical records suggest this was true, and in many of the cases medical concerns had been raised before the children were vaccinated. Hospital pathologists, looking for inflammatory bowel disease, reported in the majority of cases that the gut was normal. This was then reviewed and the Lancet paper showed them as abnormal.

How convincing was Dr. Wakefield’s article?  Vaccination rates in the UK dropped from 98% to below 80%.  Some 1350 cases of measles have been confirmed in the UK, a 2400% increase over the number of confirmed cases in 1998.

Besides the obvious implications of manipulated data, no one seemed too concerned that Dr. Wakefield’s sample in the 1998 paper included only 12 children.  Time after time after time, studies have tried to replicate Dr. Wakefield’s results.  Not surprisingly (anymore), no one was able to.  Yet, that doesn’t stop parents from receiving news time warning about vaccines, the CDC from needing to issue a statement on the safety of thimerosal, the HHS from issuing money from the vaccine injury fund (!), and major presidential candidates from telling town hall attendees that there is a “strong link” between thimerosal and autism.

I don’t even think this qualifies for an Ig Nobel award.  It’s just infuriating.

Update (2/2/10): Today, the Lancet Medical Journal officially retracted Dr. Wakefield’s original 1998 paper.  The retraction was the final domino to fall in officially discrediting the specious claim linking thimerosal and autism.  How long will it take to rid the vaccine-autism link from the minds of worried parents?  That’s a different question.  Hopefully, though, doctors can now use this to help persuade overly-worried parents that vaccines are indeed safe.

Jan 28

ARPA-E Gets a Congressional Hearing

(From L to R)
Dr. Arun Majumdar
Dr. Chuck Vest
Dr. Anthony Atti
Mr. John Denniston
Dr. John Pierce

ARPA-E is one of the newest funding programs at the Department of Energy. It was authorized in 2007 with the passage of the America COMPETES Act, but was only funded when The American Recovery and Reinvestment Act of 2009 was passed with an initial $400 million. ARPA-E is unique in that its first Funding Opportunity Announcement (FOA) was kept broad and only asked for 8-page proposals for high-risk but high-reward “transformational” technologies. Yesterday (Wednesday) in the House Committee on Science and Technology ARPA-E was examined, the chairman for the hearing was Bart Gordon (D-TN).

Arun Majumdar, the current director for ARPA-E, gave several examples why federal funding is necessary for energy research and used a graph on worldwide shipments of solar photovoltaic cells to make his point that America is losing its edge in energy technologies.

Arun also gave some metrics on the ARPA-E awards. 3,700 concept papers were received. Only 340 were invited to write a full proposal. 37 projects were selected and $151 million was pegged for those projects. 45% went to small business, 35% went to educational institutions, and 20% to large industries. Also mentioned was the start of their Fellows Program for recent PhD students interested in energy/policy.

John Pierce, the vice president of DuPont Applied BioSciences, gave a statement that called for “external advisory panels” to guide the perspective of the ARPA-E agenda. Which sounds like something industry would want.

Link to more information on the hearing: Program to Foster Innovation in Energy Technologies Is Off to a Promising Start

Link to ARPA-E: Advanced Research Projects Agency – Energy


Jan 27

Boiling in Space: What Happens in the Absence of Gravity?

(for other entries in the Chemistry in Space series, click here)

Who knew boiling a liquid was so complicated?  When you put a pot of water on the stove or heat your reaction-in-toluene solution in an oil bath several things happen.  The liquid closest to the heating element starts to get hot.  Convection circulates the hot liquid up and the cold liquid down due to the density differences of hot and cold liquids.  Eventually, the liquid near the heating element becomes hot enough to move into the vapor phase and bubbles start to form.  Buoyancy causes the bubbles to float to the surface and pop, while more convection continues to circulate the water.  Eventually, you get a rolling boil.

Everything changes in the microgravity environment of space.  Buoyancy and convection no longer play a role.  The heated fluids no longer circulate and the bubbles no longer naturally rise to the surface.  So what happens when you try to heat a liquid to boil in microgravity?  Astronauts tested this during the course of several space shuttle missions during the 1990s.  They arrived at some very interesting conclusions.

First, the liquid nearest the heating element starts to get hot, just as it does on Earth.  But it doesn’t rise and circulate due to convection.  It just gets hotter and stays next to the heating element.  It eventually gets hot enough to move into the vapor phase, just as it does on Earth, but the bubbles don’t rise to the surface and pop.  Instead, they stay next to the heating element and coalesce into one giant bubble.  Eventually, the size of the bubble becomes larger than the heating element and there is no longer any liquid in contact with the heating element.  This insulates the liquid from the heating element and leads to a “dry out” where there is no more boiling and the temperature of the heating element “begins to soar.”

(click on the image to go to the NASA page describing Zero G Boiling and to see an awesome movie of boiling in action)

All of this is predicted by theory, but it’s nice to have the chance to do some of those proof of principle experiments for the first time ever.  It reminds me of what some of the pioneers of science must have felt when working out some of the fundamental theories of chemistry and physics that we don’t even realize we take for granted today.

An interesting variation of this experiment was conducted impromptu by an astronaut on the International Space Station in 2003.  Don Pettit* was performing repair operations using a soldering iron.  He decided to put a few milliliters of water on the hot surface.  The water droplet formed a blob around the soldering iron and kinda wobbled there.  As expected, the water heated up and began to boil.  Surprisingly, though, this time the boiling looked much similar to boiling on Earth.

My working theory is the small amount of water and the inherent jostling of the system (the soldering iron looks like it was held by hand in front of the camera) caused enough motion in the water to move the bubbles around.  The bubbles could bump into each other and coalesce.  The size of the bubbles quickly reached the surface (unlike the bulk boiling experiment described above) and were allowed to pop.  Thus, it is by accident, in my opinion, that the boiling looks like it would on Earth.  It’d be interesting to repeat the experiment with the soldering iron held steady by vice grips or something.

(click on the image to go to the NASA page on the soldering iron boiling experiment and to see an awesome movie of this microgravity microboiling in action)

Here’s an overview page of boiling in space.
Here’s the NASA page on the 1990s boiling experiments.
Here’s the NASA page on the impromptu soldering iron boiling experiment.

*Also inventor of the super awesome zero-g coffee mug.

Older posts «

» Newer posts