ChemMatters Infographic: A Quick Guide to Organic Reactions

reductions in organic chemistry

To make sense of the endless variety of chemical reactions that can occur, chemists have devised many ways to categorize reactions that seemed similar. One early attempt to explain reactions related to combustion or the burning of various substances involved speculation that a fire-like substance called phlogiston was released. One big problem was the phlogiston could not be detected, and an even bigger problem was that substances that underwent combustion actually gained weight! Continue reading ChemMatters Infographic: A Quick Guide to Organic Reactions”

A Real-Life Mission to Mars

This poster outlines the major phases of the exploration of Mars.

While reading The Martian, our ACS ChemClub book study selection, it amazes me how real the story seems, even though we know humans have yet to travel to the Red Planet. But after reading the book you may have wondered how likely it is for a real mission to take place, rather that the fictional Ares Program in The Martian.

It turns out NASA is already developing the capabilities needed to send humans Mars in the 2030’s, a goal outlined in the bipartisan NASA Authorization Act of 2010 and in the U.S. National Space Policy, also issued in 2010. And it is not just NASA doing the planning, they are also working with commercial and international partners to create the Global Exploration Roadmap, which lays out a shared vision for coordinated human and robotic exploration of our solar system. In March 2017, the president of the U.S. signed a new law authorizing a manned NASA mission to Mars.

The plans for exploring are complex and have many steps, but two big pieces of technology include NASA’s powerful Space Launch System rocket and Orion, a new generation spacecraft designed to carry astronauts into deep space.

The Orion Spacecraft will carry a crew of four. It is capable of missions as near as orbits around the earth to as far as Mars and beyond. Orion will have multiple uses, from transporting crew and supplies to the International Space Station to exploring deep space. NASA’s current goal is to have Orion operational by 2021.

Space Launch System will be the most powerful rocket ever.

The Space Launch System is classified as a super-heavy launch lift vehicle. It initially will be able to carry 70 metric tons of payload into Earth orbit. Upgrades in years to follow will double this capacity. The first version is scheduled to launch in 2018.

This NASA poster is one of several promoting a future mission to Mars.

The next step in going to Mars is to build the Deep Space Gateway and the Deep Space Transport. The Deep Space gateway will be like a small version of the International Space Station but will orbit around the moon. This will serve as an assembly station and rest stop for astronauts headed for Mars. It will have several docking ports and room to amass supplies and equipment.

The Deep Space Transport is a reusable spacecraft that will be stationed at the Gateway and will depart from there. After traveling to Mars it will return to the gateway for service and refitting and another mission. Other than landing humans on the surface of Mars and returning them safely, other details of the first mission to Mars are still in development.

And if you still think this sounds like science-fiction, consider that NASA has designed a series of posters to recruit the next generation of deep space voyagers! Although they are not quite ready to accept applications, they are definitely getting the word out that the future is real.

If you have any comments or questions about plans to travel to Mars, share your thoughts with us in the comment section and on Facebook or Twitter using #ACSChemClubBook.

Don’t forget, about the resource packet for the ChemClub Virtual Book Club, including the two contests that are still open:

A Day Like No Other: Keeping Time on Mars

Those of you reading The Martian, our ACS ChemClub book selection, are aware of the special timekeeping system that is used for Mars. Instead of keeping track of time by days, it is measured in sols. The main reason for this difference is the way Mars travels through space.

Similar to Earth, Mars moves in an orbit around the sun while at the same time spinning around its own axis. There are a couple of big differences though. For one, it takes Mars about 687 days to make one trip around the sun, which constitutes one Martian year. This is compared to a year on Earth that takes approximately 365 days. The other big difference is how long it takes Mars to spin on its axis, which fictional astronaut Mark Watney points out in the book (p. 18) takes 39 minutes longer than an Earth day. This makes the Martian sol 2.7 percent longer. This might not sound like much difference, but consider that after just two weeks the change would be over 30%, or 7 hours time difference.

To avoid confusion, a day on Mars is called a sol, short for a solar day. You might wonder why this is necessary, and before our modern era of space exploration it didn’t matter as much. But as scientists built and sent remote spacecraft to orbit and land on Mars, it became very important. Spacecraft, especially those that landed on the surface, were dependent on sunlight to operate their solar cells and provide electricity. Also, it was important to know when it was light enough to take pictures or videos outside, along with many other tasks. It is also much colder during the Martian nighttime compared to the hours when the sun is up. If the scientists on Earth worked on local time, it wouldn’t correspond to time on Mars.

Some NASA scientists work and live on Martian time, an experience they found to be very disorienting and stressful. After just 18 days their noon comes at midnight, and soon they are having to sleep all day to get ready for their work sol. Perhaps it was easier for Mark Watney to adjust, considering all his clues for waking and sleeping were normal every sol. At any rate, worrying about how long his sol lasted was among the least of his concerns!

If you have any comments or questions about keeping time on Mars share your thoughts with us in the comment section and on Facebook or Twitter using #ACSChemClubBook.

Don’t forget, about the resource packet for the ChemClub Virtual Book Club, including the two contests that are still open:

 

Fermi Questions: Back of the Envelope Calculations

The Art of Estimation
When I was in high school, in the days before electronic calculators were available, we learned how to use mechanical slide rules (see ChemMatters, April 2004, p.4) for our calculations. While they were great for getting a good answer to math problems, they didn’t keep track of the decimal place. That had to be done by keeping track of an order of magnitude estimate of the answer. Continue reading “Fermi Questions: Back of the Envelope Calculations”

The Smell of Rain

After a long, dry summer, a rainstorm is often welcomed. The first rain of the season always seems special, and a bit different, especially because they are often accompanied by a unique smell. You’ve probably smelled this type of rain before. It has an earthy and sharp, sweet smell that is unlike any other. And it doesn’t happen with the rainy days that follow. The smell is distinctive enough to have its own name, petrichor, pronounced, peˌtrīkr. The February issue of ChemMatters magazine has a wonderful infographic about petrichor that was developed by an ACS ChemClub member.

This term was coined bin 1964 by two Australian researchers, Isabel Joy Bear and Richard G. Thomas, for an article in the journal Nature. The term comes from the Greek word petra meaning stone, and ichor from Greek mythology, meaning the fluid that flows in the veins of the gods.

It may seem odd that rain would have a smell at all, because rain starts out as pure water, which has no smell. Bear and Thomas reasoned the smell must have something to do with what happens as the raindrops hit the ground. They duplicated this process in their lab by drying samples of clay earth and then subjecting it to varying amounts of moisture. By analyzing the compounds that cause the odor, researchers have identified the source of petrichor.

It turns out that during dry weather, soils collect volatile plant oils (such as terpenes and fatty acids) that are released into the air when the rain lands on them.

Another contributor is the compound named geosmin, which is formed by bacteria in the soil. The human nose is very sensitive to geosmin and can detect it in as little as five parts per million (ppm).

And finally, ozone (O3) and nitric oxide (NO) that occur naturally in the air contribute to the smell of rain, as they are absorbed by the rain as it falls.

It is interesting that in India the perfume industry in the region of Kannauj hasbeen making a perfume by distilling these same elements from the clay soils in the area. it is known asmitti attar orEarths perfume. It has the same smell as petrichor.

While the chemical nature of petrichor has been well understood for several decades, it wasn’t until 2015 that scientists understood the mechanism of how the odor was released into the air. Researchers from the Massachusetts Institute of Technology (MIT) used high speed cameras to film raindrops hitting the ground. They found that when the raindrops hit the ground they form create aerosols in air bubbles inside the drop, like gases in a glass of soda pop. These bubbles burst and escape into the air, making Earth’s own perfume.

This graphic is a winning entry in the inaugural ChemClubInfographic Contest. ACS ChemClubs were challenged to take a chemistry topic and turn it into an original informational graphic. Entries were judged on originality, and the ability to convey accurate science details clearly and creatively. This infographic was conceived by Michelle Prunier from Guilderland High School in Guilderland Center, NY. It appears in the February 2017 issue of ChemMatters.