Fade to ... blue?

Back when the canoe was purple.

Fading: it sure can make things look old. Red patio umbrellas fade to pink; posters fade to monochrome; and twenty years after I bought my purple canoe, I found it was still shiny, but now it was blue! It totally changed colour. How is that possible?

Not all colours fade at the same speed. Red is the least stable, and blue seems to last longest. Why is that?

What Makes Colour & What Makes it Fade

Colour comes from pigment either naturally or by adding it. (Tulip colour is natural and paint has colour pigment added to it.) Air and sunlight break down the chemicals in that pigment colour, though, and so can the other substances the pigment is mixed with, like plastic. Sometimes a reaction creates oxygen, and that bleaches the colour too. Heat and humidity can speed this up; they tend to speed up all reactions.

Colour Wavelengths Matter

The longer the wavelength of absorbed light is (which causes the colour we see), the faster it will break down. Even the longest colour wave is stupendously small; you could fit almost 1600 wavelengths of red light into the width of a human hair.

Blue is in the 400 nm range of wavelength and red has much longer, weaker waves up in the 700 nm range. Red fades much faster than blue.

Grab your crayons or your paints and you will find that mixing blue and red makes purple. That is what my canoe builder did; she told me she mixed red and blue paint to create purple that could not be bought. Since the red part of the mixed paint degraded faster than the blue part, it resulted in a 20-year-old canoe that is blue.

The red faded from my purple canoe, leaving behind only the blue in the mixture after 20 years. The purple underneath peeks out after sanding.

Colour to Last 

If you were making something to sit outside in the sun for a long time, what colour would you make it? Look around you: Does it look like makers tried that? What colour are tarps? How about tents or sail covers?

To preserve cave paintings, we limit their exposure to light, heat, and humidity by limiting how many people can visit them. People bring heat with their bodies and humidity with their breath, as well as lights to view the paintings.

Colour to Go 

What if you wanted to get rid of colour? How could you use what you know about light and oxygen to bleach something?

How are colour fading facts being used to get this laundry bright white?

Death by Oxygen

by Adrienne Montgomerie

Flying high in the sky where the air is thin, fighter pilots wear oxygen masks to make sure they can breathe. But oxygen can be deadly. It's a tight balance.

Oxygen to Live

The air we breathe is actually mostly nitrogen (close to 4/5 of it). Only about 1/5 of the air outside is oxygen.* And what we breathe out still has quite a lot of oxygen in it. Our bodies only use about 1/4 of it.
We breathe O₂: it has two atoms of oxygen in every molecule. Add an oxygen atom, and we get O₃: ozone. High up in Earth's atmosphere, a thin layer of ozone protects us from too much harmful solar radiation (the UV in sunshine).

Oxygen to Kill

Oxygen is also used to clean water. The O₃ of ozone quickly breaks down into O₂. The free oxygen atom oxidizes cells and other pollutants in the water.
Oxidation happens when a substance joins with oxygen and turns into another substance. Rust is oxidation, so is an avocado turning brown. In cells, oxidation happens when oxygen burns through membranes and joins with the DNA inside.
Antioxidants prevent oxidation in cells, or at least slow it down. Vitamins C and E and others do this work, but with questionable results.

Can’t Live With It, Can’t Live Without It

When the air has less than 6% oxygen, humans can't get enough to live. But getting too much oxygen can be deadly too. When there's much more that 21% oxygen in the air, some of that oxygen binds to proteins in the lungs, interferes with the central nervous system, and messes with the eyes. It can lead to death. So doctors and nurses are very careful to not give patients too much.
Breathing is necessary, and oxidation is a natural process linked to aging. So, in some sense, oxygen will be the death of you.

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*There's another 1% or so of outside air that is made up of carbon dioxide and argon (mostly), plus some other gases.

Photo courtesy of Defence Imagery, CC0 Pixabay.

Struck by Lightning: Creative Insight in Chemistry

Chemical Heritage Foundation
[CC-BY-SA-3.0 (http://creativecommons.org/licenses/by-sa/3.0)],
via Wikimedia Commons

Struck by Lightning: Creative Insight in Chemistry
                   by Judy Wearing

Imagine your garden variety chemistry scientist at work. Did you conjure up a picture similar to mine? A man, in a white lab coat with several golden-brown stains on the front, or a ripped pocket. He’s well worn, and slightly careless with his appearance because he’s got better things to do with his time, i.e., make lots of precise measurements of mysterious powders and liquids, which he swirls in large beakers, very carefully because if anything splashes he’ll carry the scars of the resulting flesh wounds forever. He bends over a lot, paying close attention to his mixtures and balances, and hence has a hunched back. He is rather antisocial, or at least socially-stinted as he does not use words much in everyday life; his writing centres around equations and long names of compounds with unaesthetic suffixes like ene and ic. He is considerably less romantic than my imaginary physicist, and far more esoteric than my biologist. He is the first to leave the pub, never buys the beer, and is unlikely to believe in fairies.

I don’t know any chemists, and I cannot conjure a single scrap of remembrance of any of the half dozen undergraduate chemistry profs who tried to teach me their discipline, such was the impression they made. I am quite sure that my imagined, biased, and uninformed stereotype is false. In fact, I am ashamed that I possess it in the first place – it is wrong, and I know better, for lots of reasons, one of which is that I’ve spent a good chunk of time with scientists of many stripes. They are generally nice people of both sexes with active social lives and a range of talents and abilities. I’d be more embarrassed to admit such a stereotype if I was not convinced it is so common to possess it, and that many will recognize or appreciate aspects of the image portrayed.

This stereotype, like many others through which we unwittingly perceive the world and the people in

Friedrich August Kekule

it, affect our perception of creativity. Take the story of August Kekulé, arguably Europe’s most prominent chemist in the latter decades of the 19th century. It was Kekulé who theorized the concept of chemical structure – envisioning how atoms are arranged in molecules without any means of actually observing them. This insight was a leap forward that enabled organic chemistry to blossom. Kekulé described the moment of his best-known scientific breakthrough, the ring structure of benzene, as a daydream:

"I was sitting writing on my textbook, but the work did not progress; my thoughts were elsewhere. I turned my chair to the fire and dozed. Again the atoms were gamboling before my eyes. This time the smaller groups kept modestly in the background. My mental eye, rendered more acute by the repeated visions of the kind, could now distinguish larger structures of manifold conformation; long rows sometimes more closely fitted together all twining and twisting in snake-like motion. But look! What was that? One of the snakes had seized hold of its own tail, and the form whirled mockingly before my eyes. As if by a flash of lightning I awoke; and this time also I spent the rest of the night in working out the consequences of the hypothesis…Let us learn to dream, gentlemen."

Kekulé was not under the influence of drugs, hallucinogenic or otherwise. And his description of the

process of creative thinking is not so strange, though it does not fit with the stereotypical methodical, plodding scientist. For example, the mention of lightning figures in the descriptions of other chemists asked in a questionnaire in 1931, by two men named Platt and Baker, how they make scientific progress. “I decided to abandon the work and all thoughts relative to it, and then, on the following day, when occupied in work of an entirely different type, an idea came to my mind as suddenly as a flash of lightning and it was the solution.” Another chemist wrote, “One day all of a sudden the whole became as clear and comprehensible as if it were illuminated with a flash of light...” The mathematician Gauss described the moment when he solved a troublesome problem whose solution had eluded him for years, “like a sudden flash of lightning the riddle happened to be solved.”

These rational, scientific men are all evoking some external and sudden force to describe their creative insights. To avoid a new stereotype of chemists who stand out in the rain waiting to be struck by lightning in order to achieve scientific fame, here is how other scientists have described a moment of clarity:

“…as if from the clear sky above me – an idea popped into my head as emphatically as if a voice had shouted it.”

“in all directions…happy ideas came unexpectedly without effort like an inspiration.” Von Helmholtz, physicist

“Again and again the imaginary plan on which one attempts to build up order breaks down and then we must try another. This imaginative vision and faith in the ultimate success are indispensable. The pure rationalist has no place here.” Max Planck, physicist.

The experiences of these men and women are not reserved for the particularly fanciful or brilliant. In Platt and Baker survey of chemists, 33 % stated they received frequent assistance from intuition, while 50% occasionally experienced these insights. If you, like me, have a stereotype of the rational scientist, you will be mildly surprised by the more fanciful workings of their minds. These anecdotes suggest three conclusions:

1. creativity is important for all sorts of mental processes, across disciplines - both science and art; 
2. a person who is an excellent analytic thinker can also be an excellent creative thinker; and, 
3. at least some common aspects of creativity happen in our brain without us being conscious of it, which gives the sensation of a vanilla shock. Or, being struck by lightning.

The Wonders of Sticky Tape

On Christmas Eve, one hundred years ago, right where you are now, a child just like you might have been wrapping a present. To do so, they would need some brown paper, scissors, and a burning candle. First, the paper was cut and folded around the present. Then, hot wax from the candle was dripped between the paper’s edges. The paper was held together with a finger until the wax cooled and became smooth and hard. The wax had turned from liquid to solid. The solid wax stuck to the paper, and kept the edges together. A bit of ribbon was added to make the package pretty.  

People do not usually use wrap gifts with candle wax anymore. It is dangerous, and messy. In 1930, an American inventor named Richard Drew made wrapping gifts simpler and safer when he invented “sticky tape.”  Part of his job for the company 3M was to play with sticky stuff and see what he could invent with it. Sticky tape was the result. Now, all over the world, whenever people want two pieces of paper to stay together, they use a piece of tape. No candle required.

Tape is a long strip of plastic with a layer of glue on one side. Only one side of tape – the side with the glue – is sticky. The other side has to be smooth so the glue does not stick to it, and we can unroll it. The smooth side is the side that we touch with our fingers. When Richard Drew was thinking about how to make tape, a clear, thin plastic called cellophane had just been invented. Cellophane, also known as plastic wrap, was first used to cover leftovers in the kitchen. It is cellophane that Richard Drew used to make his see-through, sticky tape.

Tape might be simple to use, but it is not simple to make. Richard Drew had to be very patient and he tried many recipes in his search for the perfect glue. More than thirty different ingredients are in sticky tape glue. Some of these ingredients are oils and some are plastics. All these ingredients were mixed together and tested until the glue was just right.

Glue that is too sticky would not come off the roll. Glue that is not sticky enough would not hold things together.  Sticky tape glue works so well because it gets stickier when it is pushed down with your fingers. It is “pressure sensitive.” It comes easily off the roll, and then when you press it onto the paper, it stays there.

When fingers apply pressure to tape, it affects the molecules in the glue – it squishes them against the surface, causing them to spread out, just like squishing a jelly sandwich makes the jelly spread out. The glue – and the jelly – is flowing slowly, like a liquid. The harder the molecules are pressed against the surface, the more they flow, and the more they stick.

Tape sticks best to paper, glass, and metal. It does not stick as well to plastic like yogurt cups. Try it yourself; is it easier to get a piece of tape off glass, or a yogurt container? The next time you wrap a present, remember you are squishing molecules with your finger. You and your fingers are an important part of the tape’s stickiness.

The science of sticky tape is complicated. It has taken scientists a long time to understand how pressure sensitive glue works, and they still don’t have all the answers. There have been whole books written about the subject! This is one invention that works well, even though we do not fully understand how. It reminds us that even simple things can be full of surprises. Just like that Christmas present waiting for you under the tree.

The Anniversary of Silent Spring

By Claire Eamer

Rachel Carson in 1944.
U.S. Fish and Wildlife Service photo

This week marks an important anniversary. Fifty years ago yesterday - September 27, 1962 - was the official publication date of Rachel Carson’s book, Silent Spring. It was a ground-breaking, impeccably researched, and lyrically written chronicle of the damage being done to the environment by excessive use of synthetic chemicals, especially DDT. And it’s generally credited with launching the environmental movement.

Even before Silent Spring reached bookstore shelves, its friends and foes were lining up to do battle. The book had been serialized in the New Yorker magazine over the previous summer, so its contents were no secret. One of the big chemical companies threatened a lawsuit in an attempt to block publication, but Carson’s publishers went ahead anyway. With thousands of pre-orders and a spot on the Book of the Month Club roster, Silent Spring was heading for the best-seller list.

And Rachel Carson was heading into battle. She was an unlikely environmental warrior. Born in 1907, Carson was a biologist who had worked for the United States government until her successful books about the ocean made it possible for her to quit and write full-time. She was a quiet, private person who had worked hard all her life, supporting her parents, sisters, nieces, and an adopted son. Walks along the seashore and peaceful hours of writing were what she wanted – not a public platform.

Rachel Carson and Bob Hines conduct marine biology
research in Florida, 1952.
U.S. Fish and Wildlife photo

But the public platform is what she got. As soon as the book appeared, it was attacked by spokesmen for the big, powerful chemical companies, by agriculture departments, by scientists who had tied their reputations to the chemical revolution of the 40s and 50s, and by a lot of politicians who knew where their campaign funds came from. The problem facing her opponents, however, was that Carson had done her homework. Her research was solid, and she had consulted the leading experts in the United States and beyond. She had facts on her side.

Stymied in their attempts to attack the book’s content, Carson’s opponents turned to attacking its author. She was called a hysterical woman, a fanatic devotee of bird-huggers and organic gardeners, even a tool of subversive (read Communist) forces that were threatening America’s food supply by trying to ban all pesticides (a position Carson never took). It was the kind of firestorm of personal attacks that American climate scientists face today.

Through it all, Carson remained calm, polite, and eminently rational – all the more remarkable because she was desperately ill. In fact, she was dying of breast cancer, although very few people knew it. Her words, both written and spoken, won her plenty of supporters, including the American President, John Kennedy. By the time she died, just 18 months after the publication of Silent Spring, Carson knew she had made a difference and that the first steps were being taken to control the use of pesticides and other chemicals and limit their environmental impact.

For more about Rachel Carson and Silent Spring:

http://www.rachelcarson.org/

http://www.newyorker.com/online/blogs/books/2012/09/rachel-carsons-natural-histories.html

http://www.guardian.co.uk/global/blog/2012/sep/27/rachel-carson-silent-spring-legacy

Lightning Under the Hood: Part Three - From Cell Phones to Sports Cars

by L E Carmichael

Part One - Riker's Race

Part Two - The Battery Revolution

The Chevy Volt - a plug-in hybrid electric vehicle

Remember those brick-sized cell phones from movies in the 1980s? Lithium batteries are the reason we're no longer carrying them. They're also what make laptops, iPads, and MP3 players possible.

Lithium is the first metal on the periodic table, and it's 30 times lighter than lead. That also makes it a good candidate for electric car batteries, which have to pack maximum power into the lightest possible package.

As far as we know, lithium was first used in a battery in 1907, by Thomas Edison. His patent application claimed that 2 grams of lithium hydroxide in every 100 mL of electrolyte improved battery capacity by 10% and dramatically extended battery life.

It was a long time, however, before lithium batteries - Li-ION as they are usually known - could be used to power something as big and demanding as a vehicle. One of the reasons was safety. If the batteries overheat, elemental lithium can combine with water and oxygen in a reaction called "thermal runaway." This causes the battery to burst into flames.

The problem's been recognized since the 1970s, when researchers at Exxon were developing watch batteries using lithium chemistry. Their experiments were so dangerous, the fire department eventually threatened to bill the scientists for the costs involved in putting out the fires! Thermal runaway was vividly illustrated in 2011, when a plug-in hybrid electric vehicle – the Chevy Volt – caught fire several days after crash testing. As Chevy officials correctly pointed out, however, proper battery-handling protocols were ignored following the tests; in the real world, there's far less risk involved with a car powered by lithium batteries than “in carting around 15 gallons of highly flammable [gasoline].” 

An all-electric Tesla plugged in to recharge

Although scientists are still working towards newer and better variations in lithium battery chemistry, there's no denying their amazing energy potential. Martin Eberhard, cofounder of the electric sports-car company Tesla, says that for him there was never any doubt. “Lithium-ion batteries were at the top of my mind,” Eberhard says, “because in my rough calculations, you could actually fit enough batteries into a car to make a meaningful car.”

The battery pack in a Tesla Roadster contains 6,831 individual battery cells and weighs 990 pounds. That's about 200 pounds more than the lead-acid batteries in Riker's 1896 Electric Trap.  Riker's car, however, had a top speed of around 24 miles per hour, and a maximum range of around 40 miles. The Roadster's maximum speed is 125 miles per hour (artificially restricted for legal reasons), and it can travel 245 miles before it has to be recharged. Those results could never have been achieved without lithium batteries, which, by the way, are non-toxic and 60% recyclable.

They might not run on Mr. Fusion, but the cars of the future are definitely here.  Andrew Riker would probably wonder why the heck the future took so long.

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Check out the Chevy Volt, the Nissan Leaf, and Tesla Motors for more information on electric cars available for purchase today.

Lightning Under the Hood: Part Two - The Battery Revolution

by L E Carmichael

Part One - Riker's Race

Every battery has the same basic components: the anode (negative electrode); the cathode (positive electrode); and the electrolyte. There's also a separator, which prevents electrons from traveling directly from anode to cathode within the battery chamber. Instead, they exit through a wire, traveling through a lightbulb or electric motor before re-entering the battery. According to legend, when Raymond Gaston Planté invented the first battery in 1860, he used a separator made from his wife's petticoat! 

Raymond Gaston Planté

Its lacier components notwithstanding, Planté's lead-acid battery was a major breakthrough. A writer in the June 11, 1881 edition of the New York Times said, “It is quite possible that the man who has taught us to put up electricity in bottles has accomplished greater things than any inventor who has yet appeared.”

As a power source for electric vehicles, however, early batteries had some problems. Because the electrolytes were liquid, they sometimes froze in cold weather (a problem Canadian drivers still struggle with!). Hot weather was just as bad, because the water portion of the electrolyte evaporated. This meant drivers had to "top up" their batteries on a regular basis. Charles Duryea (whose gas-powered cars lost to Andrew Riker in the 1896 race) once told The Horseless Age that “A set of batteries [is] worse to take care of than a hospital full of sick dogs.”

Planté's battery

Changes to battery housings have addressed a lot of these problems, as did the invention of the block heater!  Today's gasoline-powered cars still use Planté's lead-acid batteries as starting batteries, and they were the energy source of choice for hybrids and electrics for decades. After all, lead-acid batteries are cheap and durable.  However, there's not a lot of power relative to weight.  To address this problem, scientists had to tackle the guts of the battery - the chemical reactions that produced the flow of electrons.

One alternative chemistry that seemed promising involved replacing lead with another metal, nickel.  Nickel-cadmium batteries (NiCAD) had better energy density, which meant vehicles could be driven farther and faster before having to be recharged.  However, NiCAD batteries are highly toxic and difficult to recycle. They also have what's known as memory: if NiCADs are repeatedly discharged half-way, then recharged, they eventually "remember" this partial state of charge.  As a result, the battery's full capacity can no longer be used.

Charles Duryea

Nickel metal hydride (NiMH) batteries are less toxic and less prone to memory issues. However, they're also more expensive and take longer to recharge.  Before alternative vehicles could really start competing with gas-guzzlers, a completely new battery would have to be invented. But the key breakthrough had nothing to do with cars, and everything to do with portable electronics. 

Stay tuned for the final installment - From Cell Phones to Sports Cars! 

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For more information on battery chemistry, check out Battery University.