Everyone enjoys the amazing firework shows on the Fourth of July with the beautiful vibrant colors and sparks every year. Fireworks have been part of this world for a very long time. They have been used for enjoyment and for signalling purposes. Every culture has their own significance and use of fireworks.
But all fireworks have something in common; the chemistry that makes them work. No matter where you find them, they are made up of the same compounds and are made the same way.There are ma The first use of chemical energy was in Greece, “Greek Fire” which was first reported in the 7th century A. D. It was a blend of sulfur, organic fuels, and saltpeter that generated flames and dense fumes when ignited. Around 1000 AD a scientist recognized the unique properties of another blend of chemicals called the black powder, consisting of potassium nitrate, sulfur, and charcoal; which became the first "modern" high-energy composition of black powder.
The Chinese were also involved in pyrotechnics, developing rockets by 10th century and using fireworks in 1200 AD.Chinese firecrackers became a popular item in the United States when trade begun in the 1800's, and still remain popular in the United States today, accounting for well over half of the annual sales of fireworks in this country. In the 1780's Berthelot discovered that potassium chlorate had the ability to produce brilliant flame colors using pyrotechnic compositions, and color was added to the effects of the sparks, noise, and motion previously available using potassium nitrate-based compositions. Chlorate based color-producing formulas were used in the 1830's in some pyrotechnicians' arsenals.Fireworks are a lot of fun to watch, but can be very dangerous if not handled carefully.
So to ensure safety different categories of fireworks are accessible only in certain places. The four categories of fireworks are grouped based on their gunpowder content, weight, size and how far it ejects the debris. Category 1 fireworks otherwise called indoor fireworks, include fireworks we are allowed to use in our homes. Some examples are ‘party poppers’, cracker snaps, smoke devices and small sparklers. These are the safest types of fireworks.They are safe for children to use under an adult supervision and are designed to function close to a person.
Category 2 fireworks called garden fireworks, are intended to be used in a limited outdoor space like yards or small parks where the people watching are supposed to be 5 meters from the fireworks. The fireworks in this category include small fountains, mines, wheels, rockets and large sparklers. Category 3 fireworks, also known as display fireworks, are meant to be used in big open spaces such as parks, sports fields and any kind of open land and spectators are expected to be at least 25 meters away during the firework show.This category includes fireworks such as extra large fountains, mines, wheels and rockets. Category 4 fireworks also referred to as professional fireworks, are all the fireworks not intended for the general public and they are only accessible to professionals because they require more knowledge of how and why they work in order to them. There are a lot of different types of fireworks, and that differ in content and construction.
But, there are six vital things any firework must contain: fuel, an oxidizing agent, a reducing agent, regulators, a binder and coloring agents.The fuel is made up of black powder and is used to set the chemical reaction of the firework in action. The fuel gives up the electrons to the atoms within the oxidizer, resulting in the release of atoms from the oxidizer. This forms a stable mixture that is easily combustible. When this mixture ignites it vaporizes and turns into a flame of ignition, therefore maximizing the reaction of the oxidizer.
The oxidizing agent is needed to produce the oxygen needed to burn the mixture and is usually made up of nitrates, chlorates and perchlorates.Chlorates are better oxidisers for they give up more oxygen molecules than nitrates. Perchlorates produce even more oxygen than chlorates, but do not react as easily because they are more stable. The reducing agent is needed to burn the oxygen and produce hot gases. Common reducing agents are sulfur and carbon. They react with the oxygen to form sulfur dioxide and carbon dioxide.
Regulators are used to control the speed of the reaction. This is done by adding different metal elements to the mixture. The more surface area a metal has, the faster the reaction will happen.Coloring Agents are used to add the beautiful and vibrant colors we all love to the mixture. These different colors are achieved by different metal salts used in the fireworks.
The last component of a firework is the binder. This is used to keep all of the different parts of the firework together in a consistent, paste like mixture. It binds everything together so nothing falls out of the shell. Everyone enjoys fireworks because of the beautiful colors they create.
The chemistry behind it actually pretty simple.The different colors are achieved by adding different elements to the mixture, for example: Sodium- Orange/Yellow, Strontium-Red, Barium-Green, Copper-Blue. Also, the combining of elements can be done to create even more color combinations: Strontium + Copper = Purple. Sometimes metals, such as iron, steel, zinc and aluminum are added. This adds the effect of sparks.
This happens because the flakes of metals are heated to a high enough temperature to either burn or shimmer brightly. When the different elements are heated by the hot gases surrounding them inside the firework, they produce these luminous colors.Black powder, also known as gunpowder, is the most important ingredient which has many special characteristics. It makes an amazing ignitor for fireworks. Gunpowder is the most important ingredient in all fireworks.
The ratio of the substances that make up gunpowder have remained the same since it was discovered in China about 1,000 years ago: 75 percent saltpeter (potassium nitrate), 15 percent charcoal, and 10 percent sulfur. Gunpowder is a really good ignitor because it's a "low explosive," meaning its ignition velocity is less than about 100 yards per second. "High explosives" like dynamite have a velocity of ignition is greater than 1,000 yards per second. ) Fireworks makers can also control the powder's rate of burn.
One of the easiest ways is by manipulating the size of its grains: Fine grains burn more quickly than coarse grains. Sparklers: There are two main types of sparkler: wire sparklers that are sold in many shops for most of the year and tubed sparklers that resemble pencils in shape and size. The wire sparkler might look the simpler of the two types but it can infact be the more difficult to make.First, a good quality wire must be used that will not corrode during the subsequent dipping operations or in storage. If iron or steel is used as the spark source it too must be protected from corrosion by coating with a low-viscosity oil such as paraffin. A typical gold sparkler contains iron ? lings, aluminium powder, barium nitrate and dextrin or gum arabic as a binder.
Barium nitrate is used as an oxidizer in reaction with the aluminium which acts as an energetic fuel, raising the combustion temperature; the main reaction roducts being Al2O3, BaO and N2, where the oxides produce a coherent ash that does not melt or fall from the wire. Charcoal is used as a fuel and burning rate stabilizer while dextrin(starch gum) forms a viscous dispersion in water such that it can be added to the ingredients to form a slurry that will adhere to the wires. It is normally necessary to dip the wires several times in the ingredients to get a nice thick coat. Fountains: Fountains are popular ? reworks and range from small devices of only approximately 15 mm in diameter up to professional ? reworks of 125 mm or more.Although the compositions used in fountains are usually based on black powder propellant, the sparks that are responsible for the fountain effect originate from other substances within the composition.
These substances are known as ‘emitters’ and it is the physical and chemical properties of the emitters that determine the characteristics of the fountain. Various additives are also used to promote the visual effects or to cheapen the composition. Broadly speaking, the components of the propellant react to produce hot combustion gases which heat up the particles of the emitter and eject them from the body of the ? ework. On contact with the air, the hot emitter particles ignite to produce the well known fountain effect. (Figure 1). Typical emitters which have been used in such ? reworks include carbon, titanium, aluminium, iron or a magnesium/aluminium alloy.
Antimony trisul? de (Sb2S3) is also commonly used to enhance the ‘glittering’ e? ect in a series of chemical reactions with the gunpowder and aluminium. Rockets: The initial development of the ? rework rocket and the military rocket probably occurred during the same period in history. Both used black powder as the rocket propellant.In sending a rocket into the sky we require several laws of chemistry, and the same laws apply whether the application is a small ? rework rocket weighing a few ounces or a solid propellant ‘booster’ for the space shuttle containing around 300 tons of propellant.
These fundamental processes are divided into two big categories, internal ballistics and external ballistics. In the internal ballistics when black powder is used to propel rockets it is classed as a composite propellant (where the fuel and oxidiser are mixed) and forms part of a rocket motor in which the powder is compressed to form a single grain inside a combustion hamber. (Figure 2) As well as gunpowder, the composite propellant mix will contain a binder which is used to improve the cohesion of the ingredients. Binders form a distinct phase and tend to reduce the sensitiveness of the propellant to shock and impact. In external ballistics in the propulsion of a solid propellant rocket, relatively small masses of materials are ejected through the nozzle at a very high velocity while the relatively higher mass of the rocket is propelled forward at a much lower velocity.
In the case of a rocket, the chemical reaction between the fuels and oxidisers in the propellant forces product gases through the nozzle at a certain momentum, while the momentum of the rocket increases in the opposite direction. Wheels: Wheels which are also referred to as Catherine Wheels paper pipe of the length required to make a spiral is closed at one end by twisting or folding it over. Depending on the desired effects, gunpowder with added charcoal and steel is used as a ? lling to give a glittering shower of sparks of various intensities, while aluminium or titanium can be added to boost the e? ects.In order to colour the ? ame, oxidising salts of appropriate metals can be incorporated, but the proportion of gunpowder or mealed powder is usually kept high because, in the absence of any other thrust-producers, the wheel will fail to turn. Bangers: Bangers have changed very little since Roger Bacon made the first banger, but they are no longer accessible to the general public. One of the simplest of ? reworks, the penny banger, is produced in large quantities using very small cardboard tubes where the ? rst operation is to press a clay plug into the bottom of each tube.
This is followed by applying a label.A bundle of such tubes is then inverted such that an explosive charge consisting of ? ne grain gunpowder and mealed gunpowder can be loaded in. After this a length of Bickford-type safety fuse is glued into the top of each loaded tube. Finally a mealed powder primer and blue touch-paper are applied to the fuse end. When the touch-paper is lit, the potassium nitrate, with which it is impregnated, causes the paper to smoulder until it reaches the mealed powder priming. This priming rapidly ignites, which in turn ignites the ? rst grains in the delay fuse which then burn progressively, from grain to-grain.
