Physics & Astronomy News

The 'Serpent' Star-forming Cloud Hatches New Stars
Stars that are just beginning to coalesce out of cool swaths of dust and gas are captured by the NASA's Spitzer Space Telescope.

NASA Scientists Find Evidence of Water in Meteorite
A team of NASA and JPL scientists has found evidence of past water movement throughout a Martian meteorite, reviving debate in the scientific community over life on Mars.

Physicists Discover ‘Quantum Droplet’ in Semiconductor
JILA physicists used an ultrafast laser and help from German theorists to discover a new semiconductor quasiparticle—a handful of smaller particles that briefly condense into a liquid-like droplet.

Astronomers Discover Planet That Shouldn't Be There
The discovery of a giant planet orbiting its star at 650 times the average Earth-Sun distance has astronomers puzzled over how such a strange system came to be.

You can’t get entangled without a wormhole
MIT physicist finds the creation of entanglement simultaneously gives rise to a wormhole.

more physics & astronomy news stories


by Richard M. J. Renneboog and

Image Courtesy EPA

Chemical reactions are interactions between atoms and molecules that result in a change in their relative arrangements and interconnections. The reaction affects only individual atoms and molecules, but even just a small mass of any material contains billions and billions of atoms or molecules. Just one gram of hydrogen gas, for example, contains about 602,235,900,000,000,000,000,000 hydrogen atoms! For an individual reaction to occur, electrons within atomic and molecular bonds must become 'activated' and enter a state that allows the required bonding changes to occur. This new intermediate or transitional state represents a higher energy state of the reacting atoms and molecules, and this poses a barrier to the progress of the individual reactions. Each individual reaction must overcome the 'activation energy' barrier as the overall reaction proceeds through the mass of reacting materials.

A catalyst is something that can interact with the reacting materials in such a way that the 'activation energy' barrier of the individual reactions becomes much lower. This usually occurs when reacting atoms or molecules adhere to the surface of the catalyst. The electrons of the affected molecules become partially rearranged in this association of catalyst and substrate, and in a way that is very favorable to the desired reaction. The association of catalyst and substrate is completely reversible. Once formed, the catalyst-substrate complex can dissociate in two ways: either they separate into their original unassociated forms, or they separate as the substrate completes its reaction transformation. In either case, the catalyst returns to its original form. So, while a catalyst becomes very intimately involved in the reaction process, it does not itself undergo a reaction, and is usually recovered intact after a reaction has gone to completion.

Perhaps the most readily known example of the application of a catalytic system is in the 'catalytic converter' of the typical automobile. It's purpose is to complete the combustion of gasoline residues coming from the engine. Under ideal conditions, gasoline would completely oxidized during combustion to produce mostly carbon dioxide and water. But in our less-than-ideal world, combustion is usually incomplete and the exhaust gases contain gasoline hydrocarbon molecules in various states of oxidation. These gases enter the catalytic converter where they pass through a dense honeycomb, with a very large surface area, coated with metals such as platinum or palladium that function very well as catalysts. Their atoms interact well with both hydrocarbons and oxygen, and in joining with the catalyst both become more reactive. When both are present on the catalytic surface, much less energy is needed to bring them into a reactive conformation, and reaction between them is made much easier.



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Science Quote

'There is no inductive method which could lead to the fundamental concepts of physics. Failure to understand this fact constituted the basic philosophical error of so many investigators of the nineteenth century.'

Albert Einstein
Science Sidebar | Science Education Articles
10 Ways to Keep Your Kids Interested In Science

Young children are natural scientists: they ask questions, pick up sticks and bugs outside, and are curious about the world around them. But as they get a bit older, many kids gradually lose their interest in science. They might see it as just another task at school, something that doesn't apply to their lives. Of course nothing could be further from the truth, so here are ten ways you can remind your kids that science is everywhere. Most of these are fun for adults, too! Continue reading ...

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USC University of Southern California Dornsife College Physics and Astronomy Department McMaster University Physics and Astronomy Department