Physical and Chemical Changes Involved in Fireworks
Below is a fireworks slideshow of firework shows from all around the world.
What are Fireworks?
Fireworks are explosive rockets set off or celebrations of various kinds, producing light, colors, noise and smoke. Fireworks are shot into the air by mortars or rockets, allowing many people to see the display. The original fireworks were made from gunpowder, which is a mixture of ingredients including saltpetre, sulphur and charcoal. Fireworks are ignited by fire, the firework cannot be ignited if there is no oxygen for the flame to consume.
Changes Involved in Fireworks
If you burn a certain chemical it will make a physical change which changes the colour. The metal or metals within the pyrotechnic mixture and the burning temperature dictate the color and intensity of the light. Basically, when certain metals are heated to the right temperature, electrons momentarily jump between so-called electron shells, or energy levels within the atoms. When they fall back to a lower state a photon is emitted, and the wavelength of the photon determines the color. The easiest firework colors to achieve are red (using strontium), green (barium), yellow (sodium) and white (titanium). Blues are more difficult because the temperature of the reaction has to be just right. Sparks, in contrast, are made using slower-burning mixtures, and shapes such as rings, hearts and smiley faces are made by precise placement of the pellets inside
All pyrotechnic mixtures are made up of a fuel and an oxidizer. Like black powder, the mixture usually comprises a metal nitrate and a carbon-based fuel. When the blend ignites it turns from a solid into what is predominantly gases. The reaction also gives out a lot of heat--usually in excess of 2,000 degrees Celsius for brilliant colors. A number of factors determine the speed of a firework reaction. These include the composition of the shell and other physical characteristics, such as the grain size (smaller means faster), the presence of accelerators (sulphur and sugars, for example) or retarders (salt, for instance), high pressure or confinement (which increases the reaction rate), packing density (which reduces the reaction rate) and moisture content.
Incandescence
Incandescence is light produced from heat. Heat causes a substance to become hot and glow, initially emitting infrared, then red, orange, yellow, and white light as it becomes increasingly hotter. When the temperature of a firework is controlled, the glow of components, such as charcoal, can be manipulated to be the desired color (temperature) at the proper time. Metals, such as aluminum, magnesium, and titanium, burn very brightly and are useful for increasing the temperature of the firework.
Luminescence
Luminescence is light produced using energy sources other than heat. Sometimes luminescence is called 'cold light', because it can occur at room temperature and cooler temperatures. To produce luminescence, energy is absorbed by an electron of an atom or molecule, causing it to become excited, but unstable. When the electron returns to a lower energy state the energy is released in the form of a photon (light). The energy of the photon determines its wavelength or color.
Sometimes the salts needed to produce the desired color are unstable. Barium chloride (green) is unstable at room temperatures, so barium must be combined with a more stable compound (e.g., chlorinated rubber). In this case, the chlorine is released in the heat of the burning of the pyrotechnic composition, to then form barium chloride and produce the green color. Copper chloride (blue), on the other hand, is unstable at high temperatures, so the firework cannot get too hot, yet must be bright enough to be seen.
Quality
Pure colors require pure ingredients. Even trace amounts of sodium impurities (yellow-orange) are sufficient to overpower or alter other colors. Careful formulation is required so that too much smoke or residue doesn't mask the color. With fireworks, as with other things, cost often relates to quality. Skill of the manufacturer and date the firework was produced greatly affect the final display (or lack thereof).
More Chemical and Physical Changes
Source: http://www.scientificamerican.com/article/what-are-the-physical-and/
Source 2: http://sciencefireworks.blogspot.com.au/2011/03/what-chemical-reactions-occur-in.html
Firstly, fireworks are basically constructed with firm packed with very explosive powder. This powder is designed to basically launch the firework high into the sky. While doing this, it also ensures the safety of the viewers. When a firework is launched, it is basically a missile. The first stage then burns, powering the firework. The powder that is burning is known as gunpowder. When gunpowder burns, it causes hot exhaust gas that fires backwards. The force of this gas creates an opposite reaction that sends the fireworks flying high into the air. Next, the second stage is when the firework is more looser than the first stage. The explosive material, as well as being looser, is also finer. The fuse continues to burn upward, causing this stage to be set on fire as well. The next part of the firework depends on how this stage is made. It can either explode, creating the colourful explosion or it can shoot of more firecrackers in any desired programmed directions. Fireworks always make explosions that are symmetrical. This is because of a law called the law of conservation of momentum. The firework builds up such a momentum that it must be the same before the explosion, as well as after it, therefore the explosion balances on both sides. The colour of the firework is made by the burning of various metal compounds (metallic salts) that are placed firmly inside a package.
Fireworks, which are also known as pyrotechnics, are basically devices that contain burning compounds. The most common type of display firework is the aerial shell, which is fired from a mortar tube. These fireworks typically have four components: a lift charge, a time-delay fuse, a breaking charge and a light/effect generator. The lift charge is generally black powder, a compound that burns rapidly and propels the shell from its tube. The lift charge also ignites the delay fuse when it fires. The delay fuse is usually a black powder fuse with a delay of a few seconds, and it is designed to ignite the break charge when the shell reaches the appropriate height. The purpose of the break charge, which sits at the center of the lofted shell, is to explode, thereby igniting and scattering the shell's contents. This break charge is generally finer-grained black powder than the lift charge and more highly confined, which causes the shell to explode. The payload of the shell usually comprises small spherical pellets of pyrotechnic composition designed to generate light. These capsules burn from the outside inward, and color changes are obtained by layering different compositions on top of one another.
The metal or metals within the pyrotechnic mixture and the burning temperature dictate the color and intensity of the light. Basically, when certain metals are heated to the right temperature, electrons momentarily jump between so-called electron shells, or energy levels within the atoms. When they fall back to a lower state a photon is emitted, and the wavelength of the photon determines the color. The easiest firework colors to achieve are red (using strontium), green (barium), yellow (sodium) and white (titanium). Blues are more difficult because the temperature of the reaction has to be just right. Sparks, in contrast, are made using slower-burning mixtures, and shapes such as rings, hearts and smiley faces are made by precise placement of the pellets inside the shell.
All pyrotechnic mixtures are made up of a fuel and an oxidizer. Like black powder, the mixture usually comprises a metal nitrate and a carbon-based fuel. When the blend ignites it turns from a solid into what is predominantly gases. The reaction also gives out a lot of heat--usually in excess of 2,000 degrees Celsius for brilliant colors. A number of factors determine the speed of a firework reaction. These include the composition of the shell and other physical characteristics, such as the grain size (smaller means faster), the presence of accelerators (sulphur and sugars, for example) or retarders (salt, for instance), high pressure or confinement (which increases the reaction rate), packing density (which reduces the reaction rate) and moisture content.
Fireworks are explosive rockets set off or celebrations of various kinds, producing light, colors, noise and smoke. Fireworks are shot into the air by mortars or rockets, allowing many people to see the display. The original fireworks were made from gunpowder, which is a mixture of ingredients including saltpetre, sulphur and charcoal. Fireworks are ignited by fire, the firework cannot be ignited if there is no oxygen for the flame to consume.
Changes Involved in Fireworks
If you burn a certain chemical it will make a physical change which changes the colour. The metal or metals within the pyrotechnic mixture and the burning temperature dictate the color and intensity of the light. Basically, when certain metals are heated to the right temperature, electrons momentarily jump between so-called electron shells, or energy levels within the atoms. When they fall back to a lower state a photon is emitted, and the wavelength of the photon determines the color. The easiest firework colors to achieve are red (using strontium), green (barium), yellow (sodium) and white (titanium). Blues are more difficult because the temperature of the reaction has to be just right. Sparks, in contrast, are made using slower-burning mixtures, and shapes such as rings, hearts and smiley faces are made by precise placement of the pellets inside
All pyrotechnic mixtures are made up of a fuel and an oxidizer. Like black powder, the mixture usually comprises a metal nitrate and a carbon-based fuel. When the blend ignites it turns from a solid into what is predominantly gases. The reaction also gives out a lot of heat--usually in excess of 2,000 degrees Celsius for brilliant colors. A number of factors determine the speed of a firework reaction. These include the composition of the shell and other physical characteristics, such as the grain size (smaller means faster), the presence of accelerators (sulphur and sugars, for example) or retarders (salt, for instance), high pressure or confinement (which increases the reaction rate), packing density (which reduces the reaction rate) and moisture content.
Incandescence
Incandescence is light produced from heat. Heat causes a substance to become hot and glow, initially emitting infrared, then red, orange, yellow, and white light as it becomes increasingly hotter. When the temperature of a firework is controlled, the glow of components, such as charcoal, can be manipulated to be the desired color (temperature) at the proper time. Metals, such as aluminum, magnesium, and titanium, burn very brightly and are useful for increasing the temperature of the firework.
Luminescence
Luminescence is light produced using energy sources other than heat. Sometimes luminescence is called 'cold light', because it can occur at room temperature and cooler temperatures. To produce luminescence, energy is absorbed by an electron of an atom or molecule, causing it to become excited, but unstable. When the electron returns to a lower energy state the energy is released in the form of a photon (light). The energy of the photon determines its wavelength or color.
Sometimes the salts needed to produce the desired color are unstable. Barium chloride (green) is unstable at room temperatures, so barium must be combined with a more stable compound (e.g., chlorinated rubber). In this case, the chlorine is released in the heat of the burning of the pyrotechnic composition, to then form barium chloride and produce the green color. Copper chloride (blue), on the other hand, is unstable at high temperatures, so the firework cannot get too hot, yet must be bright enough to be seen.
Quality
Pure colors require pure ingredients. Even trace amounts of sodium impurities (yellow-orange) are sufficient to overpower or alter other colors. Careful formulation is required so that too much smoke or residue doesn't mask the color. With fireworks, as with other things, cost often relates to quality. Skill of the manufacturer and date the firework was produced greatly affect the final display (or lack thereof).
More Chemical and Physical Changes
Source: http://www.scientificamerican.com/article/what-are-the-physical-and/
Source 2: http://sciencefireworks.blogspot.com.au/2011/03/what-chemical-reactions-occur-in.html
Firstly, fireworks are basically constructed with firm packed with very explosive powder. This powder is designed to basically launch the firework high into the sky. While doing this, it also ensures the safety of the viewers. When a firework is launched, it is basically a missile. The first stage then burns, powering the firework. The powder that is burning is known as gunpowder. When gunpowder burns, it causes hot exhaust gas that fires backwards. The force of this gas creates an opposite reaction that sends the fireworks flying high into the air. Next, the second stage is when the firework is more looser than the first stage. The explosive material, as well as being looser, is also finer. The fuse continues to burn upward, causing this stage to be set on fire as well. The next part of the firework depends on how this stage is made. It can either explode, creating the colourful explosion or it can shoot of more firecrackers in any desired programmed directions. Fireworks always make explosions that are symmetrical. This is because of a law called the law of conservation of momentum. The firework builds up such a momentum that it must be the same before the explosion, as well as after it, therefore the explosion balances on both sides. The colour of the firework is made by the burning of various metal compounds (metallic salts) that are placed firmly inside a package.
Fireworks, which are also known as pyrotechnics, are basically devices that contain burning compounds. The most common type of display firework is the aerial shell, which is fired from a mortar tube. These fireworks typically have four components: a lift charge, a time-delay fuse, a breaking charge and a light/effect generator. The lift charge is generally black powder, a compound that burns rapidly and propels the shell from its tube. The lift charge also ignites the delay fuse when it fires. The delay fuse is usually a black powder fuse with a delay of a few seconds, and it is designed to ignite the break charge when the shell reaches the appropriate height. The purpose of the break charge, which sits at the center of the lofted shell, is to explode, thereby igniting and scattering the shell's contents. This break charge is generally finer-grained black powder than the lift charge and more highly confined, which causes the shell to explode. The payload of the shell usually comprises small spherical pellets of pyrotechnic composition designed to generate light. These capsules burn from the outside inward, and color changes are obtained by layering different compositions on top of one another.
The metal or metals within the pyrotechnic mixture and the burning temperature dictate the color and intensity of the light. Basically, when certain metals are heated to the right temperature, electrons momentarily jump between so-called electron shells, or energy levels within the atoms. When they fall back to a lower state a photon is emitted, and the wavelength of the photon determines the color. The easiest firework colors to achieve are red (using strontium), green (barium), yellow (sodium) and white (titanium). Blues are more difficult because the temperature of the reaction has to be just right. Sparks, in contrast, are made using slower-burning mixtures, and shapes such as rings, hearts and smiley faces are made by precise placement of the pellets inside the shell.
All pyrotechnic mixtures are made up of a fuel and an oxidizer. Like black powder, the mixture usually comprises a metal nitrate and a carbon-based fuel. When the blend ignites it turns from a solid into what is predominantly gases. The reaction also gives out a lot of heat--usually in excess of 2,000 degrees Celsius for brilliant colors. A number of factors determine the speed of a firework reaction. These include the composition of the shell and other physical characteristics, such as the grain size (smaller means faster), the presence of accelerators (sulphur and sugars, for example) or retarders (salt, for instance), high pressure or confinement (which increases the reaction rate), packing density (which reduces the reaction rate) and moisture content.
Watch this video of fireworks at the 4th of July celebration in America.