Tag Archives: Chemistry

DIY Eggshell Geodes

Geodes, seemingly ordinary rocks hiding pockets of crystals inside, have fascinated amateur geologists for centuries, but did you know you can make your own geodes with just what’s in your kitchen?

diy geodes

Materials:
Eggs
Something to hold the eggs (a piece of the carton works well for this)
Water-soluble solid (salt, sugar, baking soda, etc.)
Food coloring
Water
Saucepan
Heat-resistant container

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Process:
Crack eggs as close to the narrow end as possible to save as much shell as you can
Heat water to nearly boiling and pour it into the egg, cooking the membrane inside so you can remove it. (if you don’t remove the membrane, it will mold and turn the crystals black)
Bring your water to a boil in the saucepan, gradually adding about half as much salt by volume as you have water
Keep adding salt until no more dissolves into the water
Add the mixture to your eggshells
Add the food coloring to each egg
Wait a few days for the water dissolve
Admire your results

So how does this exactly work? When you’re boiling the water, you’re adding energy to it in the form of heat, allowing it to dissolve more of the solid than it normally would. At this point, there’s so much solid (in our case salt) dissolved in it that there’s nearly no space left between molecules. This now “super-saturated” solution gradually loses energy as it cools down, forcing the solid out of solution slowly. This slow release allows the solid to instead build a growing network of crystals inside and outside the eggshell. This is actually a similar process to how geodes form in nature: water with dissolved minerals seeps into air pockets inside rocks, slowly depositing the minerals as the water flows through the rock. Try it for yourself!

DIY Polar Opposites

Oil and water won’t mix no matter how hard you try. They have different densities and different polarities. But what happens when you mix oil and milk?

Milk is an emulsion. It is made of mostly water with lipids throughout. Lipids are organic compounds that are fatty acids or their derivatives and are insoluble in water but soluble in organic solvents.

DIY Opposites

DIY oppositeWater is a “polar” molecule, meaning that there is an uneven distribution of electron density. Water has a partial negative charge (-) near the oxygen atom due the unshared pairs of electrons, and partial positive charges (+) near the hydrogen atoms. Due to the polarity, the attractive forces are very strong in water molecules. Oil is nonpolar, which means the attractive forces are pretty neutral.

diy spinning

Any liquid, to be able to mix with another needs to have nearly equal amounts of attractive forces among the molecules of both liquids. When you add oil to a bowl of milk something bizarre and amazing happens. You will see hundred of spheres form. The spheres are drops of milk which are surrounded by a layer of oil. These are technically bubbles!

But these bubbles are pretty hard to pop. You can even stir them and see how they move through the layer of oil! Give it a try for yourself.

Written by: Mimi Garai

 

DIY Limestone Caves

Most stone is made over millions of years, cooked in the core of our planet. That stone then erodes over time due to wind, acids found in rain and groundwater, and other natural weatherings. Chalk is a type of limestone formed by the shells of microscopic marine organisms.

diy caves

The process of erosion can produce beautiful features in earth’s crust, like arches, stacks, and caves. This process usually takes tens of thousands of years.

But we can make a limestone cave in just a matter of minutes. All you need for this DIY chalk cave is a block of chalk and vinegar.

cave diy

2CH3CO2H(aq) + CaCO3(s) > 2Ca(CH3CO2)2(aq) + CO2(g) + H2O(l)

cave diy crazy

The vinegar, a weak acid, reacts with the calcium compound, dissolving it. It then forms carbon dioxide gas, water, and an aqueous calcium solution. This same process takes place for real caves, but the acid in rain and ground water is much more diluted, therefore taking much much longer to see the results.

diy cave pic

Written by: Mimi Garai

 

DIY Chemistry: Coca-Cola and Milk

Mixing different liquids together to see what they taste like seems like a part of human nature. But have you ever mixed your favorite drinks together just to see if a chemical reaction will occur? This is an experiment that you can easily DIY, but we do not recommend drinking it. All you need is a bottle of coke and a bit of whole milk.

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Pour the the milk into the full bottle of coke to top it off and then put the cap back on. Mix gently and then keep an eye on it for about an hour.

chemistry

There is a chemical reaction that occurs between the Phosphoric Acid in the coca-cola and the calcium in the milk.

3Ca + 2H3PO4 ///\\\ Ca3(PO4)2 + 3H2

The reaction creates a precipitate, or solid matter, that is more dense than the liquids, therefore sinking to the bottom of the bottle. This precipitate is mostly just milk that has curdled, or become a solid.

chemistry 5

Now that you have separated the liquid and precipitate, try mixing them back together. A simple way to do this is by simply removing the bottle cap. There was a build of pressure in the bottle due to the chemical reactions. Once the bottle cap is removed the change in pressure allows the mixture to recombine. Enjoy!

Written By: Mimi Garai

The Cleaning Secret of Bleach


If you’ve ever done laundry, you know that bleach stains dark clothes and brightens light ones, but why does it do that? Well, the answer is all down to chemistry.

Bleach 1

Inside the dyes we use in clothes, food, etc., there are chemicals called chromophores. These chromophores reflect a specific wavelength of light, causing them to appear a certain color, like purple in the case of the water in our video.

Bleach

However, when bleach is added to the equation, it goes through a process called oxidation, releasing oxygen molecules. This oxygen reacts with the chromophores, breaking up the chemical bonds between them. With their bonds broken, the chromophores reflect less color, an altered color, or even a wavelength of light outside the visible spectrum depending on the type of dye in use. The reduced or invisible color reflection is just seen by our eyes as white, making light colors look lighter, and the stronger dyes like the dark purple water shift to another color, appearing as a bleach stain on our dark clothes.

 

What Makes a Hot Air Balloon Float?

It’s one of those basic rules we grow up hearing: hot air rises and cool air sinks, but why is that? If you’ve seen our piece on buoyancy, you know that density is one of the key factors in whether an object sinks or floats in a given substance, but a substance’s density doesn’t have to remain the same. The secret is in the name itself: hot air balloon. By altering the temperature of the air inside, we decrease its density, allowing it to float. Since setting off a hot air balloon would be too expensive and a floating lantern is a fire hazard, we showed this same effect by altering the temperature of a helium balloon to prevent it from floating in air.

This all ties back to something in physics called the Ideal Gas Law, which can be expressed as PV=nRT; pressure x volume = number of moles of a substance x the gas constant x temperature.

air balloon

In the case of a hot air balloon and the helium balloon, “n,” “R,” and “P” are not changing, we can focus on volume and temperature. By decreasing the temperature of the helium balloon, the volume must also decrease. Since density is described as mass divided by volume, as volume decreases, density increases. With enough drop in volume, the helium balloon becomes too dense to float.

air balloon 1

After being removed from the liquid nitrogen, the balloon slowly heats back up to room temperature. As it heats up, it returns to its original volume and floats back to the ceiling.

The reverse is true in a hot air balloon, with its density starting equal to the air outside it. As the air inside it is heated, its density decreases to the point where it has so much buoyant force lifting up on it that it can lift not only the balloon but the basket and passengers as well. When it’s in the air, the operator has to make sure the air stays at a consistent temperature for them to maintain altitude, with an increase or decrease in temperature will lead to an increase or decrease in altitude respectively.

DIY Soda Battery

Elementary school students the world over are familiar with potato batteries or lemon batteries, but did you know you can make a battery from soda? With just some wire, two different kinds of metals, and your favorite soda, you can build your own battery!

All you need to do is connect your metal plates to one another with a wire (or connect them to a multimeter as well to measure the battery’s voltage like we did) and place your plates into the soda. Make sure your plates aren’t touching during this experiment because if they touch, the electrons won’t flow through the wire and you won’t see a voltage register on the multimeter.

With our battery, the two metals we’re using are zinc and copper, as zinc is more reactive with the soda than the copper is; leading to a more significant voltage produced by the battery. You could also use the aluminum of the soda can, but you would need to remove the coating from the can with steel wool, as it is designed to prevent the aluminum and soda from reacting with one another. You need two different metals because if both plates are reacting with the soda the same amount, there’s no need for electrons to flow between them and therefor very little voltage produced like you see below when we try making a battery with two copper bars.

To understand how the voltage is generated, let’s take a look at the soda itself for a second. Within the soda is phosphoric acid; the key ingredient to this whole process. That phosphoric acid is breaking up into positive hydrogen ions and negative phosphate ions. Those phosphate ions are attracting the positive nuclei of the zinc and copper atoms, but copper holds its atoms together a little better than the zinc. As a result, a lot of electrons from the now separated zinc atoms are left over in the bar, some of which flow through the wire into the copper bar and establish an equilibrium.

The zinc bar is now fairly close to neutral, but the copper is more negative, so it attracts the positive hydrogen ions which remove some of the excess electrons and combine to form hydrogen gas. That gas floats up through the soda and out of the system. This process is happening in a continuous, rapid cycle so electrons are always flowing from the zinc to the copper.

Over time, the copper bar will start to become slightly positive and will repel some of its positive ions into the soda, some of which will encounter the excess electrons on the zinc bar and form a black coating of copper and copper oxide around the zinc. When that has gone on long enough, the zinc in the soda will be completely coated in copper and the voltage will look like our attempt with two copper plates above, eventually killing the battery.
When we tried with a different soda, Sprite, the voltage produced was roughly the same, but the battery lasted a lot longer because of the stronger acid in the Sprite. Grab your favorite soda and see how much voltage you can generate!

DIY: Fascinating Properties of Dihydrogen Monoxide

Humans are approximately 60% dihydrogen monoxide. If this is alarming, it might be helpful to know that this is just waterWhile water is certainly something quite familiar, it has a lot of properties that are very important and they all come from its famous chemical formula, H2O. Let’s take a look and try to understand a few.

Water molecules−which you can see an illustration of on the right−are made up of one Oxygen atom and two Hydrogen atoms. When atoms are bonded together, they do so because of electric charges. In this case, each hydrogen atom has one electron that it shares with the oxygen atom. Electrons carry a negative charge, and are held closer to the oxygen atom. This gives the oxygen atom a negative charge while leaving the hydrogen atom slightly positive. As you have almost certainly hear, opposites attract. These opposite charges pull on one another which keeps the water molecule together amidst a microscopic sea of atoms.

Due to this and the shape of the water molecule, each has a negative part where the oxygen is and a positive part where the hydrogen is. Scientists call molecules like this polar, and it is this polarity that gives rise to many of water’s unique and important properties!

The polar water molecules orient to one another and are held together by the electric attraction of opposite charges, which you can see in the illustration above.. This is important for us: If this were not the case, water would not be a liquid at room temperature at all! The relatively light water molecules would fly off as a gas because the molecules would have no attraction between them. Without this very important property, there would be no life as we know it. This attraction of water molecules to one another is called cohesion. They can also stick to many other objects by the same process, a property known as adhesion.

These two properties come together in the video above. The water molecules stick to the string, but also to one another. This allows the water to be poured at strange angles, and none of it would happen if it wasn’t for that fascinating little molecule, dihydrogen monoxide.

Recycling: Turning Styrofoam to Glue

Today is America Recycles Day, which you can learn more about recycling here. We wanted to take this opportunity to learn something cool about one of the most heinous landfill residents: styrofoam. This lightweight convenient insulating material has found many uses, from takeout containers to disposable coolers. Unfortunately, to go along with all of its good qualities, it has one bad one: it doesn’t degrade naturally. This means that when it goes in the trash, it will stay there for a very long time. In addition, styrofoam is about 95% air, each pound that is disposed of will be taking up a lot of space–possibly up to 30% of the total volume–in our garbage for the foreseeable future.

1024px-acetone-3d-vdwFortunately, not everyone is resigned to this fate. Instead, people have been trying to come up with a better way to deal with this. One of these ways uses acetone. Acetone is an organic molecule made up of carbon, hydrogen, and oxygen, and is the simplest member of the ketone family. On the right is a picture of acetone at the atomic level.

Most of the uses of acetone revolve around a single property: it is an excellent solvent. This means that it does a great job of dissolving many different kinds of molecules, making it useful as a cleaning agent in chemistry labs and a remover of nail polish.

dissolve

Styrofoam is made of polystyrene, which in itself means a chain of styrene. Styrene is a relatively simple organic molecule that can easily bind with itself. When it comes in contact with acetone, the polystyrene chains fall apart. However, the acetone doesn’t actually dissolve the styrene molecules. If it did, all of the styrofoam would disappear into the acetone, but instead we end up with this.

glue

Depending on your point of view, this probably looks like some combination of gross, scientific, and fun. Additionally, it is also useful. Using solvents like acetone to break down styrofoam can repurpose it to being a rather useful adhesive. Being able to use styrofoam as a glue is a terrific alternative to having it fill up or landfills.

Please don’t rush out and try to do this on your own, as acetone is dangerous and also not the right chemical to do this properly. To learn more about this method go here.

The Easiest UV Detector Ever

Science is full of words to describe the glowing process. We use bioluminescence for the glimmer of plankton, phosphorescence for the slow, ghostly shine of glow-in-the-dark toys, and fluorescence for pigments that emit light while exposed to just the right energy source.

screen-shot-2016-09-21-at-2-17-50-pm

L to R: Fluorite sphere with phosphorescent coating, Don Mengason, Gemological Institute of America Inc.; bioluminescent phytoplankton on Vaadhoo Island in the Maldives, Kriss-Anne Gayle, Penn State University; mineral specimen fluorescing under UV light, James A. Van Fleet, Bucknell University.

Unless you live on a coastline rich with bioluminescence, fluorescence is the glow you’re most likely to encounter in everyday life. It’s present in white materials exposed to a blacklight and in the neon glare of highlighter ink. Tonic water appears colorless under visible light, but a distinct fluorescent glow appears when it’s bombarded with ultraviolet radiation!

screen-shot-2016-09-21-at-2-20-29-pm

 

Tonic water contains a fluorescent compound called quinine. Expose quinine molecules to UV rays and they get excited, or gain energy. Excited molecules modify the absorbed light and eventually re-release it. Unlike the invisible incident radiation, the emitted glow is apparent to the human eye.

tonicgif

Test this idea for yourself by taking tonic water outside on a sunny day! The blue glow is more obvious when compared to a glass of tap water– consider setting one up as a control. For more intense fluorescence, up the UV radiation by exposing your experiment to a blacklight.

Written By: Caela Barry

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