Saturday, January 2, 2010

Make Potassium Nitrate from Lite Salt

Potassium nitrate (saltpeter) is used for many chemistry projects, most notably for making smoke bombs. I've talked about how you can obtain potassium nitrate at a store or online, but you could make it yourself from easy-to-find ingredients. NurdRage has a YouTube video of this simple inorganic chemical reaction (as well as many other cool chemistry videos).
Potassium Nitrate Ingredients
  • 40 g ammonium nitrate (from an instant cold pack which has ammonium nitrate listed as its ingredient)
  • 37 g potassium chloride (sold as a salt substitute, with potassium chloride listed as the ingredient)
  • 100 ml water
Make Potassium Nitrate Aqueous solutions of ammonium nitrate and potassium chloride are reacted to exchange the ions and form potassium nitrate and ammonium chloride. The ammonium chloride is much more soluble in water than the potassium nitrate, so you will get potassium nitrate crystals, which can be separated from the ammonium chloride solution.
NH4NO3 + KCl → KNO3 + NH4Cl
  1. Dissolve 40 g of ammonium nitrate into 100 ml of water.
  2. Filter the solution through a coffee filter to remove any undissolved material.
  3. Heat the solution with 37 g potassium chloride to dissolve the lite salt. Do not boil the solution.
  4. Filter the solution and either set it in the freezer to chill or else put it in an ice bath so you can observe the crystallization of the potassium nitrate.
  5. Pour off the ammonium chloride solution, leaving the potassium nitrate crystals. You can recover the ammonium chloride, too, if you like.
  6. Once the potassium nitrate crystals are dry, you can use them for chemistry experiments. The resulting potassium nitrate does contain impurities, but it will work fine for pyrotechnics projects and other experiments described on this site.

How Do You Remove Salt from Water?

I've been asked "How do you remove salt from water?" enough times that I suspect finding the answer to the question is a common science assignment. So... how do you do it?
You can boil or evaporate the water and the salt will be left behind as a solid. If you want to collect the water, you can use distillation. One way to do this at home would be to boil the saltwater in a pot with a lid. Offset the lid slightly so that the water that condenses on the inside of the lid will run down the side to be collected in a separate container. Congratulations! You've just made distilled water. When all of the water has boiled off, the salt will remain in the pot. Evaporation works the same way, just at a slower rate.

1919 - First artificial transmutation of an element

Ernest Rutherford became the first to transmute one element into another. He bombarded nitrogen atoms with alpha particles to create oxygen using the reaction:

α + 14N → 17O + 1p

January 3 Science History

2004 - Mars rover Spirit lands on Mars.

NASA's Mars Exploration Rover landed on the surface of Mars. It was designed to act as a wandering robotic geologist to sample the soil in the area near its lander. The original plan was for the rover to travel for 40 meters a day with a lifetime range of 1 kilometer, but is still operational as of its six year anniversary.

On This Day in Science History - January 2

Charles Hatchett

January 2nd is Charles Hatchett's birthday. Hatchett was an English chemist who was the first to discover the element niobium. He was working for the British Museum and analyzed a sample of the mineral columbite when he identified a previously unknown element he called columbium. His claim was refuted when another English chemist named William Hyde Wollaston claimed Hatchett's columbium was just another form of the element tantalum. The element was later rediscovered by Heinrich Rose and named niobium.

Hatchett stopped working as a scientist and took over his father's business as Royal coach builder. Find out what else occurred on this day in science history.

Wednesday, December 30, 2009

Smoke Bomb Materials

The smoke bomb you would purchase from a fireworks store usually is made from potassium chlorate (KClO3 - oxidizer), sugar (sucrose or dextrin - fuel), sodium bicarbonate (otherwise known as baking soda - to moderate the rate of the reaction and keep it from getting too hot), and a powdered organic dye (for colored smoke). When a commercial smoke bomb is burned, the reaction makes white smoke and the heat evaporates the organic dye. Commercial smoke bombs have small holes through which the smoke and dye are ejected, to create a jet of finely dispersed particles. Crafting this type of smoke bomb is beyond most of us, but you can make an effective smoke bomb quite easily. There are even colorants you can add if you want to make colored smoke. Let's start out with instructions for the easiest/safest type of smoke bomb you can make:
Smoke Bomb Materials

  • sugar (sucrose or table sugar)
  • potassium nitrate, KNO3, also known as saltpeter (buy it online or you can find this at some garden supply stores in the fertilizer section, some pharmacies carry it too)
  • skillet or pan
  • aluminum foil
Once you've gathered your smoke bomb materials, it's easy to make the smoke bomb...
  1. Pour about 3 parts potassium nitrate to 2 parts sugar into the skillet (5:3 ratio is also good). Measurements don't need to be exact, but you want more KNO3 than sugar. For example, you can use 1-1/2 cups KNO3 and 1 cup sugar. If you use equal amounts of KNO3 and sugar, your smoke bomb will be harder to light and will burn more slowly. As you approach the 5:3 KNO3:sugar ratio, you get a smoke bomb that burns more quickly.

  2. Apply low heat to the pan. Stir the mixture with a spoon using long strokes. If you see the grains of sugar starting to melt along the edges where you are stirring, remove the pan from the heat and reduce the temperature before continuing.

  3. Basically you are carmelizing sugar. The mixture will melt and become a caramel or chocolate color. Continue heating/stirring until the ingredients are liquefied. Remove from heat.

  4. Pour the liquid onto a piece of foil. You can pour a smaller amount onto a separate piece, to test the batch. You can pour the smoke bomb into any shape, onto an object, or into a mold. The shape and size will affect the burning pattern.

  5. If you aren't going to clean your skillet immediately, pour hot water into the pan to dissolve the sugar (or else it will be harder to clean). Clean up any residue you may have spilled out of the pan, unless you want mini-smoke bombs on your stovetop.

  6. Allow the smoke bomb to cool, then you can peel it off the foil.
Now that you've made your smoke bomb, it's time to light it...

Homemade Firecracker Materials

Firecrackers are extremely easy and inexpensive to make yourself. You may want to make your own firecrackers because you are interested in learning how to make simple fireworks or it may be you are unable to obtain fireworks where you live. Fortunately, the materials needed to make your own firecrackers are very common.

Homemade Firecracker Materials

Toy gun caps are nice because the powder used in them is easy to work with. Here's how to get the powder out of the caps:
  1. Gently insert a pin or needle through the back of a cap through to the front.
  2. Remove the pin and re-insert it from the front, where you made the hole. Pry the powder out of the cap, tapping it onto a sheet or paper or plate or other working surface.
  3. Carefully work the pin around the edge of the cap to collect all of the powder. There is a very slight chance of popping the cap, so be gentle and work slowly.
  4. How much powder you need depends on the size of firecracker you plan to make. One ring of caps is more than sufficient to create a loud bang, but you really only need powder from about 3 caps for each firecracker. For the sake of safety, it's best to make one firecracker at a time (you don't need a big pile of powder).
Now let's assemble the firecracker.
One you have all of the materials necessary to make firecrackers, you are ready to start putting the firecrackers together.
  1. Take a piece of tape about 2" long and pick up the gunpowder on the sticky side of the tape. Evenly coat the tape until you either run out of gunpowder or else run out of stickiness.
  2. Place the fuse (about 2 inches long) so that it sticks halfway down the tape. The fuse does not need to stick to the tape.
  3. Roll the tape around the fuse. Take another piece of tape and tightly wrap your firecracker. Be sure to cover the bottom of the firecracker or else the opening will give you a small rocket rather than a popping firecracker.
Alternatively, you could just fold a 2-inch strip of paper in half lengthwise, pour the gunpowder into the fold of the paper, and wrap the paper around the fuse. The paper firecracker could be secured with any kind of tape.

Now that you have a homemade firecracker, you need to light it! This is basically the same as lighting any other firecracker. Make sure you light it on a firesafe surface, far from people or pets. Don't hold the firecracker in your hand when you light it. Firecrackers that you buy contain measured quantities of gunpowder. You can estimate the amount of gunpowder in your firecracker based on how many caps you used. You won't necessarily get a louder 'bang' using more gunpowder, but you will increase the potential risk of injury, so don't go crazy making big firecrackers. Have fun!

Make New Year's Fireworks

'm partial to smoke bombs, since they are easy to make and don't explode, but there are lots of other fireworks you can make for your New Year's Eve celebrati

What Happens If You Touch Dry Ice?

Dry ice is the solid form of carbon dioxide, which normally exists as a gas. It is extremely cold (-109.3°F or -78.5°C), so you can get frostbite from touching dry ice... but what if you just want to poke it or touch it for an instant? What happens if you taste it?
Here's the answer.

Answer: When dry ice heats up it sublimates into carbon dioxide gas, which is a normal component of air. The problem with touching dry ice is that it is extremely cold (-109.3°F or -78.5°C), so when you touch it, the heat from your hand (or other body part) is absorbed by the dry ice. A really brief touch, like poking dry ice, just feels really cold. Holding dry ice in your hand, however, will give you severe frostbite, damaging your skin in much the same manner as a burn. You do not want to try to eat or swallow dry ice because the dry ice is so cold it can 'burn' your mouth or esophagus, too.If you handle dry ice and your skin gets a little red, treat the frostbite like you would treat a burn. If you touch dry ice and get frostbite such that your skin turns white and you lose sensation, then seek medical attention. Dry ice is cold enough to kill cells and cause serious injury, so treat it with respect and handle it with care.

So What Does Dry Ice Feel Like?

Just in case you don't want to touch dry ice, but do want to know how it feels, here's my description of the experience. Touching dry ice is not like touching normal water ice. It is not wet. When you touch it, it feels somewhat like what I would expect really cold styrofoam would feel like... sort of crunchy and dry. You can feel the carbon dioxide sublimating into gas. The air around the dry ice is very cold.
I have also done the 'trick' (which is inadvisable and potentially dangerous, so don't try it) of putting a sliver of dry ice in my mouth to blow carbon dioxide smoke rings with the sublimated gas. The saliva in your mouth has a much higher heat capacity than the skin on your hand, so it isn't as easy to freeze. The dry ice does not stick to your tongue or anything like that. It tastes acidic, sort of like seltzer water.

Tuesday, December 29, 2009

Prevent a Hangover

The other day I mentioned a study that found the severity of a hangover is related to the color of the alcohol, which was a reflection of the chemical composition of the drink. There's more to hangover chemistry than just the color of the drink, however. For example, some people's biochemistry essentially makes them immune to hangovers. These people can detoxify the alcohol, acetaldehyde, and congeners quickly enough to escape most of the negative effects of alcohol consumption, except maybe the effects of dehydration, since the enzymes responsible for clearing the body of alcohol and its metabolites require water.

If you are not a member of that lucky 25-30% of people who don't get hangovers, you can minimize your chances of suffering by avoiding deeply colored drinks, staying hydrated, and limiting your consumption. Keep in mind, some alcoholic beverages contain enough contaminants that it's not the alcohol that gives you the hangover, so even one drink might be enough to make you sick. If you do find yourself suffering from your holiday celebration, there are several hangover remedies you can try.

Sunday, December 27, 2009

The Nobel Prize in Chemistry 2009

"For studies of the structure and function of the ribosome"

Photo: MRC Laboratory of Molecular Biology
Credits: Michael Marsland/Yale University
Credits: Micheline Pelletier/Corbis
Venkatraman Ramakrishna
Thomas A. Steitz
Ada E. Yonath
third 1/3 of the prize
third 1/3 of the prize
third 1/3 of the prize
United Kingdom
MRC Laboratory of Molecular Biology
Cambridge, United Kingdom
Yale University
New Haven, CT, USA; Howard Hughes Medical Institute
Weizmann Institute of Science
Rehovot, Israel
b. 1952
(in Chidambaram, Tamil Nadu, India)
b. 1940
b. 1939

The Nobel Prize in Chemistry 2009

Prize Announcement

 Announcement of the Nobel Prize in Chemistry by Professor Gunnar Öquist, Secretary General of the Royal Swedish Academy of Sciences, 7 October 2009.






 Following the announcement, Professor Gunnar von Heijne told senior editor Simon Frantz how the achievements awarded the 2009 Nobel Prize in Chemistry not only provided insights into life at the atomic level, but also provided insights into how to save lives.



The Nobel Prize in Chemistry

In 1901 the very first Nobel Prize in Chemistry was awarded to Jacobus H. van 't Hoff for his work on rates of reaction, chemical equilibrium, and osmotic pressure. In more recent years, the Chemistry Nobel Laureates have increased our understanding of chemical processes and their molecular basis, and have also contributed to many of the technological advancements we enjoy today.