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October 23, 2002

For more information on these science news and feature story tips, please contact the public information officer at the end of each item at (703) 292-8070. Editor: Roberta Hotinski

Missouri Girl Scouts Try Their Hand at Solving Chemistry Mysteries

Junior Girl Scouts; caption is below
Junior Girl Scouts conduct hands-on chemistry experiments.
Credit: Rebecca Bergfield, University of Missouri

If chemistry professor Sheryl Tucker had her way, the Girl Scouts would offer a chemistry badge.

In the Heart of Missouri Girl Scout Council, several hundred Junior Girl Scouts (10-12 years old) are selected each year to participate in Tucker's "Magic of Chemistry" program at the University of Missouri, Columbia. Tucker makes science fun--with hands-on projects such as "Chemistry of Color," which involves tie-dying, secret writing and chromatography, and "Fun with Polymers," in which they experiment with glue, rubber and "slime." In October 2002, to celebrate National Chemistry Week, the girls will solve "The Case of the Unsigned Letter" by analyzing ink and other substances on a letter.

Tucker gives the Girl Scouts patches for their uniforms, T-shirts and scientific notebooks.

This educational program is supported by Tucker's CAREER grant from the National Science Foundation (NSF) and by the American Chemistry Society (ACS), non-profit and community groups and lots of volunteers. In 2002, the ACS recognized one of Tucker's programs as the best local event promoting women in chemistry. The two programs she runs each year are timed to coincide with National Chemistry Week, sponsored by the ACS, and National Girl Scout Week.

"This program is designed to ignite and retain girls' interest in science at an age when national studies indicate they begin to lose this curiosity," said Tucker. "I'd like to help remove the obstacles that might prevent young women from going into the physical sciences, particularly chemistry." Tucker attributes her interest in providing opportunities for children to explore science and chemistry to the educational emphasis of NSF's CAREER program. The CAREER awards support promising young scientists pursuing innovative research and education projects early in their careers.

The program volunteers include female undergraduates and professors that serve as role models, Tucker added. [Amber Jones]

For more information about "Magic of Chemistry" see: http://www.chem.missouri.edu/tucker/GS-page.html
For more information about National Chemistry Week see: http://chemistry.org/portal/Chemistry?PID=acsdisplay.html&DOC=ncw\index.html

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Washing Water With Soap: Entire Undergraduate Chemistry Class Publishes Results

In Steven Regen's organic chemistry class at Lehigh University, Penn., students not only carry out research, they get their results published. For the fourth time, all of his undergraduate lab students have been included as co-authors of an article about original polymer chemistry research published in a major scientific journal. The National Science Foundation (NSF) supports Regen's chemistry research involving undergraduates.

The recent class's research experiment on "hydrophobic sponges" was published in the American Chemical Society's journal Macromolecules. The class created soap-like polymers that absorb organic molecules from water. The soap molecules were attached to insoluble polymer beads and thus could be removed from the water, bringing the absorbed organic molecules along. The technique is potentially useful for removing organic contaminants from groundwater and drinking water.

All 70 students are cited in the paper.

"Professor Regen has created an innovative and rewarding learning environment," said NSF program manager Tyrone Mitchell. "What the students learn about the requirements of research that leads to publication can be quite different from their experience in a conventional classroom. At the same time, these undergraduates contribute to cutting-edge research."

"I do this to show large numbers of students how research really works, including the publication process," Regen said. "It takes the laboratory class from the ordinary to the extraordinary and shows them how class from the ordinary to the extraordinary and shows them how exciting science can be." [Amber Jones]

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Chemist Pulls Power Out of Thin Air

It makes up most of the air around us and has been studied since the 18th century, so who would have thought there'd be something new to learn about nitrogen? Fortunately, Karl Christe of the Air Force Research Laboratory at Edwards Air Force Base in California did, and now he's added to a string of NSF-funded discoveries at the Loker Hydrocarbon Research Institute of the University of Southern California by creating five-sided particles of nitrogen atoms that have potential as powerful rocket propellants.

Pure nitrogen occurs naturally only as molecules of two nitrogen atoms bound together in a form called "dinitrogen." But groups of more than two nitrogen atoms do exist bound up with other elements. If those molecules are broken out of compounds, they explosively revert to normal nitrogen. For example, sodium azide contains a group of three nitrogen atoms and is used as a solid propellant for automobile airbags. An impact triggers an explosive release of dinitrogen gas that expands the airbag in a few hundredths of a second.

Christe, working with colleagues at the University of Southern California and the Air Force Research Laboratory, has been creating molecular fragments made of five nitrogen atoms in hope of combining them to create a whole new form of nitrogen. When pulled apart, all 10 atoms of this "polynitrogen" would convert back to dinitrogen, releasing a lot of energy and nitrogen gas that could be harnessed for propulsion.

Because they're violently explosive on their own, the molecular fragments need to be stabilized with chemical "wrappers." Earlier, the team successfully created positively charged five-nitrogen atom fragments and safely stowed them in a salt. Now they've detected a negatively charged counterpart that's a perfect pentagon of nitrogen atoms and are looking for another suitable wrapper. Once they have enough of the positively and negatively charged pieces, they hope to combine them into polynitrogen.

Christe predicts that, if they can produce it, the explosive power of the polynitrogen salt would be twice that of conventional explosives. Plus it would be very clean, having only nitrogen gas as a byproduct. Conventional solid rocket boosters leave acid contrails, but a polynitrogen propelled rocket's exhaust would be practically indistinguishable from the air around us. Because it's expensive and hard to make, though, he says that it will only be used for specialty space and military applications. [Roberta Hotinski]

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The Solution to Dissolution

illustration of the dissolution of hydrogen bromide by water molecules; caption is below
Illustration of the dissolution of hydrogen bromide four water molecules are enough to start the dissolution of the acid molecule.
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(Size: 14KB)

Larger versions (Total Size: 41KB) of all images from this story

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How many water molecules does it take to dissolve an acid? Although this may sound like a joke from a Mensa meeting, it's a fundamental problem for chemists. Now with the help of a powerful laser, NSF-sponsored researcher A. Welford Castleman, Jr. of Penn State University and colleagues have found the answer: Five.

Knowing how substances dissolve is a basic chemistry problem that's key to processes ranging from chemical reactions in the body to depletion of the ozone layer. Scientists have puzzled over the process for over one hundred years and theorists had recently predicted that about four molecules of water were necessary to break an acid molecule into two charged pieces. Until now, though, there was no experimental evidence to compare with theory.

Postdoctoral scholar Sean Hurley, along with graduate students Troy Dermota and Darren Hydutsky, shone light on the subject by using a "femto-second" laser to monitor the dissolving acid. The laser puts out pulses one quadrillionth of a second long, letting the researchers observe lightning-fast interactions between molecules of the strong acid, hydrogen bromide, and water molecules. Their results indicate that four molecules of water are needed to start the breakup, and that five molecules are enough to complete the process.

"We've been dissolving acids since ancient times, so you'd think we'd know how this works already," said Castleman. But until arrival of the femto-second laser device, there was no way to monitor reactions in great enough detail to know for sure. Ahmed Zewail, who won a Nobel Prize for pioneering the field of "femtochemistry," calls the Penn State team's work " a welcome contribution" and "an elegant study of a century-old problem."

The research is particularly important for studies of ozone loss in the Arctic. Although the infamous "ozone hole" occurs in the Antarctic, ozone depletion also occurs at the North Pole near the Earth's surface due to the influence of bromine. Ozone levels in the Arctic "can drop to almost nothing in one day," says James T. Hynes of the University of Colorado at Boulder and the Ecole Normale Superieure, Paris. The acid reaction the Penn State team studied, he says, is thought to play a critical role in this loss. [Roberta Hotinski]

For more information on the Penn State team's research see: http://research.chem.psu.edu/awcgroup/

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