Glow Sticks and Highlighters and Skin Cancer, Oh My!

Chemistry is all around us. Every time someone eats chocolate, every time a pesticide is used, every time an oil painting dries, chemistry is at play. We often don’t think about how this amazing and intricate world around us works on a molecular level: we accept that it works and move on. However, understanding how and why the world works the way it does can help us make it better. And understanding how things work can help us relate seemingly unrelated matters.

There is a fantastic website called Compound Interest, which educates people of all and any background regarding the chemistry that makes up their every day worlds. On this blog, I found a particularly interesting article about glow sticks.

We all know how glow sticks work right? You snap the little tube and all the sudden it glows so brightly and brilliantly. When I was little glow sticks were magic, a magic which I could control with the bending of that little stick. But I always wondered why breaking the stick made it glow. Turns out glow sticks glow because of a chemical reaction we set into process by snapping the tube.

Glow sticks are made up of two compartments, each with a different chemical solution. One compartment is glass and is inside of the other. The outer compartment usually contains a diphenyl oxalate compound and a dye that corresponds to the desired color. The solution inside the little glass container is hydrogen peroxide. When you bend the stick, the glass container breaks and releases the hydrogen peroxide, which then reacts with the diphenyl oxalate. When diphenyl oxalate and hydrogen peroxide react, diphenyl oxalate is oxidized and produces the unstable compound 1,2-dioxetanedione. This product is so unstable that it quickly decomposes into carbon dioxide, releasing energy in the process.

Where do the colors come from? The answer is the process of chemiluminescence. The dye itself thus far has been uninvolved in the reaction, however, at this point the electrons of the dye’s molecules absorb the released energy and become excited. When the excited electrons fall back to their ground state, they release energy in the form of light. The type of dye determines the color perceived. The stick stops glowing when one of the reactants, either diphenyl oxalate or hydrogen peroxide runs out and the reaction stops.

So glow sticks work because of dye and a chemical reaction. What else “works” because of dye? This is where another article I found comes in: the chemistry of highlighter colors. 

The color of a highlighter depends on the type of dye used, much like a glow stick. But how do chemicals and colors relate? Chemicals appear colored because they absorb some wavelengths of light and not others. When a molecule has a large amount of alternating single and double bonds, it is called a highly conjugated molecule, and it can an absorb visible wavelengths of light. The color seen depends on the wavelengths of visible light absorbed. So highlighter inks are colored because of alternating types of bonds within a molecule which allow for absorption of visible light. However, many dyes have this property yet are not fluorescent like highlighters. So why are highlighters fluorescent?

Highlighters are fluorescent because they do not just absorb visible light on the electromagnetic spectrum; they absorb UV wavelengths as well as visible ones. The light excites the dyes’  electrons which eventually fall back to their ground states, releasing energy as light in the process. This released light has a longer wavelength than that of the originally absorbed, so what was absorbed as UV light is released as visible. (Visible light has a longer wavelength than UV, making it less energetic and able to be seen by the human eye. Thus when the light released has longer wavelength, we are able to perceive what used to be low wavelength UV light). So fluorescence is the product of UV light being absorbed and released as visible light.

These two topics are incredibly related. Both glow sticks and highlighters appear colored because electrons are excited, either with energy from a reaction (glow sticks) or energy from light photons (highlighters), and then said electrons fall back to a ground state and release energy as a specific wavelength of visible light. The electromagnetic spectrum catalogues the different “types” of light if you will. It expresses the range of wavelengths and properties of radiation. Imagine a wave, on which little packets of energy, called photons, ride. The shorter the wavelength, that is the distance between the crests of a wave, the higher the frequency. Frequency measures the amount of wave cycles that pass within a given amount of time. Higher frequency means greater energy. Ultraviolet light, which falls directly above violet on the visible spectrum, has a shorter wavelength and higher frequency than visible light. So the amount of energy delivered in UV light is greater than in visible light.

Energy is needed to excite an electron, which means to raise it from a lower energy orbital to a higher energy orbital. Of course the electron cannot maintain that higher energy level forever, so it eventually falls back to it’s initial state. When it falls, the difference in energy between the orbitals is released. This energy is released as photons, which have a specific wavelength based on the material being excited. The visible spectrum corresponds to the 400 to 700 nm wavelength area of the electromagnetic spectrum. Chemicals need a certain amount of energy to excite an electron, which is taken from a specific wavelength delivering the needed amount. The wavelengths which are absorbed (used to excite the electrons) are not seen by the naked eye. Everything else is reflected. For example, when everything but red is absorbed by the fabric of a sweater, red is reflected and thus the color we perceive the sweater to be.

In examining glow sticks and highlighters, another topic came to mind: skin cancer. Now what on earth do highlighters and glow sticks have to do with skin cancer? Light. UV rays are harmful to skin because the high energy rays excite electrons within cells, which can mutate regular DNA into harmful, cancerous DNA.  About  99% of non-melanoma skin cancers and 95% of melanoma cancers are caused by too much UV exposure.   It’s amazing to think that the light that makes highlighters so fluorescent also causes skin cancer! I find these previous two topics related to skin cancer because they all are based off of energy expressed as light. Some of this is harmful, like when skin is exposed to high energy light. Some of this light is just beautiful and used as entertainment for children or as a study tool for college kids. It is amazing to see how the same basic chemical principle is expressed in so many different ways.

In studying chemistry, even the most different of subjects can be found to be related. As a potential art major, I never invested too much in chemistry growing up. But the more I learn about chemistry, the more I learn about the world. I am studying real, pressing issues and am connecting dots I thought impossible. It’s pretty amazing the connections you can make with a basic understanding of chemistry and a good website to turn to. I encourage everyone to read just one of these articles a week and see if you don’t find something that blows your mind or changes the way you live your life. Personally, I will be piling on the sun screen.


Chemistry Matters and So Does Communication

At 12:15 AM, in the wee hours of a Thursday morning, I was driving to Walmart. I had a presentation for my chemistry 131 lab in less than eight hours on chocolate and its health effects. It definitely affected me. One of those effects of meticulously preparing was the sudden urge for decadent bars of cocoa and milk. So determining that I just could not sleep until my urge for chocolate was met, and justifying it with the new information I had about chocolate’s antioxidants, I grabbed my keys and jogged to my car. I was inspired, but not just by a want for sweets.

I wanted to stand in front of the rows of Hershey and Cadbury and soak in the new information I’d gained. This one was 60% cocoa: it probably had milk and extra cocoa butter added for taste. This one was 72% cocoa: better. This milk chocolate was probably stripped of it’s anti-oxidation properties with a long roasting time: how unfortunate. In my studies of something as simple as chocolate, chemistry had breathed life and interest into a world yet unexplored.

I wanted to share that feeling with my classmates, but presenting can be very difficult. It is always nice to speak about half way through the line up. You get a chance to evaluate others and make adjustments to your own plan. I, however, was chosen first. After I finished my talk I sat down and anxiously wondered how I’d done and how other people would present differently than I had.

These are my observations and comments on the top three presentations.

Maybe I’m biased because of my sweet tooth, but Hannah did a fantastic job. She spoke on candy and how manipulating the sugars structure affects the candies texture. Her slides had a good amount of information on them; the amount of text was not overwhelming and it helped to follow along with her explanation. She spoke at a good volume and made eye contact. She obviously knew her topic well and did not rely on reading prompts. Her explanations of how different candies are made were concise and easy to understand. She paced herself well, and offered a helpful recap at the end of her presentation.

The second presenter that I thought did especially well was Wesley. He spoke about paintball. He was funny and engaging, but not unprofessional. He made good eye contact, interacted with the audience, and varied his voice so he was not monotonous. He also knew his topic well. His organization was easy to follow and he offered a great thought provoker at the end of his presentation: he not only summarized his topic but related chemistry to our everyday lives. He made an attempt to tell me not only about paintball, but about how paintball and it’s chemistry are related to the world around me.

The third presentation with which I was enamored was by Tyler, who talked about hair products. Like Hannah, he used his slides well but did not read off them. He made eye contact, did not stumble with concepts or words, so it was obvious that he was well prepared. He was engaging with good volume and variation within volume. What I admired most was how he outlined his presentation simply at the beginning and then offered a restatement that was not too chemically dense. It was more simple and compact and it was easy to take away something especially if you weren’t very interested chemistry.

Overall, I ranked these presentations the highest because of a few common characteristics: they were engaging, well rehearsed, well organized, and they attempted to answer the question of why their subject mattered.

Learning from our peers is just as important as learning from our own mistakes and victories. And in listening to others, I have decided on a course of action to help me improve my own presentation skills. Generally, I want to be better at communicating big pictures and at staying clear and concise. I think that by listening to other people, I am made aware of certain faults in presenting that I would have overlooked in myself. This is learning by example and comparison. I will be a better presenter in the future because I can carefully examine my presentation based off how I felt regarding others and judge my own with the same standards. For example, as critical as I am of another’s presentation I should be of my own. I will carefully examine my own presentation for flaws in this way, and I want to take the best qualities I saw in others and make them my own. Watching peers is a great way to learn and grow.

I think that if I follow the examples set by the best presenters, I can stay engaging, clear, and concise. And most importantly, I think it well help me to recreate the amazing experience in other people that I had learning about chemistry . If I communicate the information well, I think I can share that experience of excitement and epiphany with my peers.

Communication is integral to being human. We communicate ideas and facts and feelings. This experience presenting in lab showed me just how important it is to be comfortable communicating to large groups.

Chemical Free? More Like Scientifically Inaccurate

Science is so often misunderstood. When a title like “chemical” enters common parlance, many people become alarmed. If it’s “chemical”, it’s toxic, right?  Expert marketers know how to cater to these views. How often do you see “chemical-free”, “all natural”, etc on a label as a badge of honor? Just walk through Walmart and you will see how these claims are lauded. In particular, I saw this product: “Climb On! Bug Drug 100% Pure, Chemical Free Insect Repellent”. This name is inappropriate from a scientific standpoint. Click on the link if you’d like to see for yourself.

Chemistry is the study of matter, its composition, transformations, and properties. All matter is made up of chemicals. Water is a chemical compound, no matter what unpolluted mountain stream it came from. With this label, the marketer is attempting to portray the product as safe and reliable. When we think of chemicals, we think of spills, and toxins, and horrible side effects.  By labeling the product as “chemical-free”, the bug spray is separated from all those negative associations, even though, technically, it is not chemical-free.

So what should we call these things? The bug spray may be free of synthetic concoctions, but it surely isn’t chemically free from a scientist’s perspective. Perhaps a more appropriate label would be “free from certain chemicals”, or “no extra chemicals”. “No extra chemicals” sounds like a good name. This would represent the product as free from certain commonly added chemicals, but also acknowledge that the product itself, as matter, contains chemicals.

It is amazing how these little tricks of language affect our daily lives. What we buy at the store is often influenced by our own ignorance and the marketer’s ability to play off the fads of the day. I’d like to end with an anecdote by David Foster Wallace about understanding the world around us: “Here are these two young fish swimming along, and they happen to meet an older fish swimming the other way, who nods at them and says, “Morning, boys, how’s the water?” And the two young fish swim on for a bit, and then eventually one of them looks over at the other and goes, ‘What the hell is water?'”

So often we are unaware of what surrounds us. In that quote, fish are oblivious to water. For us, we are swimming in chemicals without even realizing it. They are in everything, and being aware of that fact can help navigate our daily lives; we don’t have to be afraid of chemicals they way so many are, especially when it comes to buying bug spray.