Monthly Archives: March 2015

DIY Fluorescent Bubbles


If you’ve ever seen objects under a blacklight – like clothes or highlighters – you may have noticed that some things glow when they’re hit by that kind of light, and others don’t. The things that are glowing are fluorescing! Fluorescence in this case is caused by an interaction between high energy UV light (from the blacklight) and some of the electrons in that object. When that high energy light strikes the object, those electrons are able to absorb the energy from the light for a short period of time. However, the electrons soon let go of that energy, emitting it as a slightly lower energy light. The light that they release is the glowing that we see!

Today at Astrocamp, we wanted to see if we could make fluorescent soap-bubbles. It not only worked, but also turned out to be pretty easy and something you can do at home! We’ll show what we did, step by step, so that you might be able to recreate this experiment yourself!

Making the Fluorescent bubble mixture:

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Materials:

  • Bubble Solution. We made our own with dish soap and water. If starting with bubble solution, skip steps 1 & 3!
  • Fluorescent Highlighters. Yellow tends to work best!
  • Bubble Wand
  • Blacklight
  • A knife or scissors

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First, add a bit of dish-soap so a container. We used a small styrofoam bowl, but you can use whatever you like.. A tablespoon of soap should be enough, but you may need more depending on the amount of water you add later.

Second, carefully cut the back-end off of a highlighter and remove the inkpad. You will need an adult for this part! Then do your best to squeeze as much highlighter-ink as you can into the bowl. In our experiment, we used a yellow highlighter. To cut our highlighter, we used a pair of scissors. For brighter bubbles, add more ink to your mixture by removing the inkpad from more highlighters! You will probably get a bunch of ink on your hands. Don’t worry! It is non-toxic, and will make you look very cool with the blacklight!

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Finish up your bubble mixture by adding water. Your bubble mixture should appear still appear “soapy” after adding water. If you think you added too much water, add more soap!

Lastly, to make the mixture fluoresce, you’ll need a black light and a dark room. To make the bubbles, you’ll need a bubble wand. If your bubbles aren’t working well, add more soap or water. If they aren’t very bright, you can add more highlighter. One was enough for this video, but your blacklight may not be as bright.

What you’re seeing
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When you’re blowing your bubbles and seeing them glow under the blacklight, you’re seeing fluorescence! The electrons from the atoms in the highlighter-ink are absorbing the high-energy, invisible UV light from the blacklight and emitting it as a slightly lower energy light that we can see – as a bright glowing.

Fire & the History of Matches


NOTE: DO NOT TRY THIS AT HOME!

Humans have been creating and controlling fire for almost a million years! Our early ancestors used friction – essentially rubbing sticks together – to create their first fires for cooking food and making tools. Today we can carry fire making tools around in our pockets.  Every year 500 billion matches are used in the United States alone. Even though we’ve come a long way from rubbing sticks together, matches today work on a very similar principle – friction. For an example of this, you can try rubbing your hands together. You should feel them get warm. It should not start a fire.

Match bodies are made of wood or stiff paper, to provide fuel for the fire. Match heads are coated in phosphorous based compounds that catch fire when heated up. The heat that lights a match generally comes from friction when you rub or “strike” a match on a rough surface. Early “strike anywhere” matches were coated in white phosphorous, but the white phosphorus was too easy to light. This made them rather dangerous, as they tended to ignite accidentally. Great if you needed to light a fire in a hurry…but not so great if you need to ship them long distances, or keep them for a long time.

Match

To get a combustion reaction like this to start requires something in chemistry called “activation energy”. This simply refers the amount of energy needed to start the reaction. These matches lit so easily because the white phosphorous in the match head needed very little energy to light. Simply rocking around in a crate could cause enough friction to ignite them. Today’s strike anywhere matches use a less dangerous form of phosphorous (phosphorous sesquisulfide). They can still be lit on any surface rough enough to create the right amount of heat from friction, but anyone who has tried (and failed) to light a match multiple times can tell you it takes a bit more effort.

In the video, the bright parts you see as the fire moves along consuming all of the matches is this phosphorus beginning to ignite. It doesn’t last very long, and its job is just to keep the match burning long enough for it to get hot and start burning the wood, which is what sustains most of the flame that you see in the end!

Fire

Liquid Nitrogen & Glowsticks

Note: Opening glowsticks is not a particularly great idea. They contain bits of broken glass and some unpleasant chemicals that can be hazardous to your health! Read full article to learn more.

Glowsticks are incredibly fun, but how do they work!? Naturally because of some very cool science, notable chemistry. Glowsticks are made up of an outer plastic casing with a smaller glass casing inside. The plastic tube is filled with a dye which determines the color of the glowstick and a chemical called diphenyl oxalate. The glass tube contains hydrogen peroxide, the same thing you might use to clean out a cut or scrape.

Glowsticks

When you crack the glowstick you break the glass, the hydrogen peroxide is released into the mixture. This causes a series of chemical reactions to take place. The main end products of this chemistry are carbon dioxide and energy, as well as another molecule we will talk about later. The energy that is released goes into the dye, which converts the chemical energy into light energy! The reaction happens slowly, so that the glow lasts for a long time. Companies can vary the amount of each chemical to have glowsticks that glow brightly for a short time or more dimly for a very long time!

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It also forms something called phenol that is a somewhat toxic chemical. Repeated exposure to this chemical, and even its vapors can be dangerous. This is why breaking open a glow stick without proper protection is not advisable. There will be phenol and broken glass in the mixture, neither of which are good things to have around! We were very careful, and used protective equipment on our skin as well as working in a well ventilated area to keep ourselves safe!

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One interesting thing is that this reaction can be stopped by extreme cold. Check out what happened when we left the glowsticks in liquid nitrogen for a while! Science!

The Leidenfrost Effect

 
Have you ever played air hockey? There is something strangely satisfying about how the puck slides effortlessly across the table, before finally coming to rest. This same thing happens naturally as well, and its actually some pretty cool science. Lets check out how it works!

When things of different temperatures interact, the warmer object loses its heat to the cooler object. This simultaneously warms up the colder thing, and cools down the warmer thing. This shouldn’t be surprising. Its the reason that snow melts in your hands and make your hands feel cold. However, when things are of vastly different temperatures, it can get a little strange.

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In the video, we are dripping water onto a stovetop that is around 500℉. The water is only about 50℉, but the important part is that the boiling point of water is around 200℉ (technically 212℉ but Astrocamp is at an elevation of about 5600’, which actually lowers the boiling point to almost exactly 200℉) which is much lower than the temperature of the stove.

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When the drops of water hit the stove, the part that hits first is immediately vaporized because of the difference in temperature. This means that the little droplet of water now has a little barrier of water vapor between itself and the stovetop, which it can float around on. The water droplets seem to bounce and skitter around without boiling away. This is what we call the Leidenfrost Effect. For water, this seems to occur at temperatures of at least 400℉.

It is the same thing that allows a person to pour liquid nitrogen over their hand unharmed (Don’t try this at home), or dip their hand in water and then dip it in boiling hot lead (DEFINITELY don’t try this at home)! Cooks sometimes use this to estimate the temperature of their pans and see if they are ready to cook.

Fireproof Balloon & How it Changed the World

 
The balloon in the video isn’t anything special. It’s a completely normal balloon filled with completely normal water. However, water is quite extraordinary!

We describe matter by listing its different properties. Some of these properties include how dense something is, its flexibility, its ability to conduct electricity, and even its color! Another less commonly known (but just as important!) property is called “specific heat”. This property is one of the things that makes water really interesting!

Specific heat indicates how difficult it is to heat up or cool down an object. For example, if you were to put two pots on a stove and fill one with air (by leaving it empty) and fill one with water, the air one would heat up much quicker even though the stove is adding the same amount of energy to each one! The water doesn’t heat up nearly as much while being given the same energy, meaning it has a very high specific heat.

This is exactly what happens in the video. The match is hot enough to melt the rubber and form a hole, causing the balloon to pop immediately! It actually pops before the fire even reaches the surface.Fire2!

With the water balloon through, the entire balloon can be engulfed in flame, and nothing happens! This is because the water absorbs the energy from the hot flame, but doesn’t heat up very much. The rubber never heats up enough to melt.Fire!

Specific heat works the other way too. Water also takes a long time to cool off. In this way, the specific heat of water actually shapes the climate on a global scale. Take a look at the image below. The snow cycles are much more visible in the Northern hemisphere because they only have to go over land. Ground has a lower specific heat than water, so during the winter it cools down more easily, allowing the cold to pass further south forming ice over most of the Northern continents. In the Southern Hemisphere, the water is much more difficult to cool down, and the icy chill barely even reaches the land!

Earth Seasons Specific Heat (1)

A Breathing Earth” by John Nelson, using images from NASA’s cloud free satellite imagery of Earth.

Bernouli’s Ping Pong Ball Experiment

 
Using a hair dryer to levitate a ping pong ball is a classic do it at home science experiment.  It utilizes two basic principles to keep the ball hovering in the air.  The first principle is the transfer of momentum from the moving air particles to the ping pong balls.  Basically, the moving air hits the ball and exerts a force upwards on the ball.  This is fairly intuitive straightforward.  Bernouli’s Principle is the law responsible for keeping the ball contained in the airstream and it is much more complex and interesting.

Bernouli’s principle states that the faster a fluid or a gas move around an object, the less pressure they exert on it.  What this means for the ping pong ball is that as the air moves around it, there is less pressure pushing on it from the sides.  However, if the ball tries to leave the airstream (because of the collisions from the moving air or due to gravity) it will encounter some stationary air that exerts a higher pressure back on the ping pong ball.  Essentially the ball is encountering a wall of static air that bounces the ball back into the airstream.  Now because the wall is made of air it doesn’t take too much force to break the barrier, but as long as you keep the hair dryer fairly steady you should be able to keep the ping pong ball levitating for a while.  Sadly there were no hair dryers back in Bernouli’s day, but we’d like to think he would have fun with this experiment if he did.  Enjoy!

WELCOME TO OUR ASTROCAMP BLOG

We would like to thank you for visiting our blog. AstroCamp is a hands-on physical science program with an emphasis on astronomy and space exploration. Our classes and activities are designed to inspire students toward future success in their academic and personal pursuits. This blog is intended to provide you with up-to-date news and information about our camp programs, as well as current science and astronomical happenings. This blog has been created by our staff who have at least a Bachelors Degree in Physics or Astronomy, however it is not uncommon for them to have a Masters Degree or PhD. We encourage you to also follow us on Facebook, Instagram, Google+, Twitter, and Vine to see even more of our interesting science, space and astronomy information. Feel free to leave comments, questions, or share our blog with others. Please visit www.astrocampschool.org for additional information. Happy Reading!

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