It’s a bird! It’s a plane! It’s Superglue!

Courtesy of Ifoundouttoday.com

Things break, that’s just how the world works. While materials like wood or metal can be mended with rivets, nails, or screws, other materials are not repaired so easily. Enter: superglue. When things like mugs shatter, pots break, plastic pieces snap, superglue is here to save the day! If you’ve ever accidently got some on your fingers and stuck them together, you know just how powerful this adhesive can be. But what makes this substance so sticky, and how can such small amounts of it be so strong?

Superglue isn’t your everyday Elmer’s. Firstly, many traditional glues, such as Elmer’s, work through what is known as solvent evaporation. In this process, a polymer (a long repeating chain of chemical units known as monomers) such as polyvinylacetate, is first suspended in a water solution (this solution is what you purchase in the store). When the solution is applied to a material and exposed to air, the water from the solution begins to evaporate. Eventually, all of the water evaporates, leaving behind a layer of flexible polymer. Superglue, however, goes through a process known as curing, in which a chemical reaction actually takes place!

The main component in superglue is a chemical called cyanoacrylate. When exposed to air, water droplets in the air initiate a process known as anionic polymerization.  First, a water droplet attacks the carbon-carbon double bond in cyanoacrylate, pushing a pair of electrons onto one of the carbons. Now, this carbon has more electrons than it needs, and therefore has a negative charge (electrons have a negative charge), and is referred to as an anion. To get rid of this negative charge, this carbon then attacks a nearby molecule of cyanoacrylate, causing a new negative charge to form. This process continues until all of the molecules of methyl cyanoacrylate have reacted, creating a network of long chains of polycyanoacrylate. It is this multitude of bonds that gives superglue its super strength!

Ten Facts about Super Glue: http://www.supergluecorp.com/blog/2010/05/17/10-fun-facts-about-super-glue/

References:

• chm233.asu.edu/notes/halides/
• http://home.howstuffworks.com/question695.htm
• http://books.google.com/books?id=OZ6CbJlsJM8C&pg=PA1131&lpg=PA1131&dq=chemistry+of+superglue&source=bl&ots=Qp4NViO9bD&sig=OdYbttoZuBTnBY9t06CKfsmpItI&hl=en&sa=X&ei=-ob8UJboAuGT0QGAioCgBg&ved=0CE8Q6AEwAw#v=onepage&q=chemistry%20of%20superglue&f=true

Boom Goes the Dynamite

Happy New Year Everyone! I apologize for the wait, but we’re back again, and with the New Year come new resolutions, so expect consistent updates! In celebration of the New Year, today I’ll be discussing fireworks. They light up the sky on special occasions creating colors and shapes to amaze, but what is it that produces this brilliance? From sparklers to aerial fireworks, it’s a wide world of bright lights!

From sparklers to aerials, all fireworks are made up of the same few components: an oxidizing agent, a reducing agent, a coloring agent and binders. In order to burn the mixture and create the various colors and patterns, fireworks need a fuel source: the oxidizer. Oxidizers, usually composed of nitrates (NO3-), chlorates (ClO3-) or perchlorates  (ClO4-) release oxygen by reacting and exchanging electrons with metal ions (an example of this is shown below).

                                                4KNO3     ------->    2K2O + 2N2 + 5O2

Of these oxidizers, nitrates are the least reactive but also the most controllable. As such, nitrates are used as the major component of black powder, the compound responsible for thrusting the firework high into the sky. The less stable chlorates, react more intensely, producing an explosion upon reaction rather than a consistent burn. Although chlorates are used in fireworks, they are relatively unstable, giving them limited use. Their most stable counterparts, however, perchlorates, are more stable and produce more oxygen, making them ideal to produce the brilliant explosions found in fireworks. 

The oxygen released from the oxidizing agents then quickly reacts with the reducing agents, typically either sulfur and carbon (charcoal). These reactions produce hot and rapidly expanding gases, either sulfur dioxide or carbon dioxide respectively, adding to the explosive force of the reaction.  It is the heat and force generated from this reaction that produces the loud explosions and bright colors characteristic of fireworks.

The colors of fireworks are created by heating metal salts such as strontium carbonate, barium chloride, and copper(I) chloride, each of which produces a unique color. Energy from the combustion of the reducing agents excites electrons within the metal atoms into a higher energy state. The electron then falls back to its ground state, emitting a characteristic wavelength of light with a specific color. Depending on the salt used, a wide range of colors can be produced!

Red	strontium salts, lithium salts lithium carbonate, Li2CO3 = red strontium carbonate, SrCO3 = bright red
Orange	calcium salts calcium chloride, CaCl2 calcium sulfate, CaSO4·xH2O, where x = 0,2,3,5
Gold	incandescence of iron (with carbon), charcoal, or lampblack
Yellow	sodium compounds sodium nitrate, NaNO3 cryolite, Na3AlF6
Electric White	white-hot metal, such as magnesium or aluminum barium oxide, BaO
Green	barium compounds + chlorine producer barium chloride, BaCl+ = bright green
Blue	copper compounds + chlorine producer copper acetoarsenite (Paris Green), Cu3As2O3Cu(C2H3O2)2 = blue copper (I) chloride, CuCl = turquoise blue
Purple	mixture of strontium (red) and copper (blue) compounds
Silver	burning aluminum, titanium, or magnesium powder or flakes

                                                                                                                                                 courtesy of about.com

The anatomy of a firework is relatively simple. A fuse runs out of the firework allowing an observer to ignite the ignition charge from a safe distance. Once lit, the fuse, composed of a fast action and time delay fuse, quickly ignites the lift-off mixture. As mentioned before, the power needed to thrust the firework into the air is provided by black powder, a combination of sulfur, charcoal (carbon) and potassium nitrate.  As the firework rockets into the sky and reaches its apex, the time delay fuse ignites a burst charge, similar in composition to black powder, which creates a large explosion. This explosion propels small clay like balls, known as stars, flying. These stars contain the oxidizing-reducing-metal salt combination that produces the colorful patterns we all enjoy! Who knew that so much went into lighting up the night sky! 

How fireworks are made!

References:

• http://library.thinkquest.org/15384/chem/index.htm
• http://chemistry.about.com/od/fireworkspyrotechnics/a/fireworkcolors.htm
• http://science.howstuffworks.com/innovation/everyday-innovations/fireworks.htm
• http://scifun.chem.wisc.edu/chemweek/fireworks/fireworks.htm