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Colored fire is a common pyrotechnic effect used in stage productions, fireworks and by fire performers the world over. Generally, the color of a flame may be red, orange, blue, yellow, or white, and is dominated by blackbody radiation from soot and steam. When additional chemicals are added to the fuel burning, their atomic emission spectra can affect the frequencies of visible light radiation emitted - in other words, the flame appears in a different color dependent upon the chemical additives. Flame coloring is also a good way to demonstrate how fire changes when subjected to heat and how they also change the matter around them. [1] [2]
To color their flames, pyrotechnicians will generally use metal salts. Specific combinations of fuels and co-solvents are required in order to dissolve the necessary chemicals. Color enhancers (usually chlorine donors) are frequently added too, the most common of which is polyvinyl chloride. A practical use of colored fire is the flame test, where metal cations are tested by placing the sample in a flame and analyzing the color produced. [3] [4]
Color | Chemical | Image |
---|---|---|
Red | Strontium chloride or strontium nitrate | |
Orange | Calcium chloride | |
Yellow-green | Barium chloride | |
Orange-yellow | Sodium chloride (table salt) | |
Apple green | boric acid | |
Green | Copper(II) sulfate and boric acid | |
Blue | Copper(I) chloride and butane | |
Violet | 3 parts potassium sulfate, 1 part potassium nitrate (saltpeter) | |
Blue/light violet | Potassium chloride | |
White/Yellow | Nitromethane [5] |
Emitted colors depend on the electronic configuration of the elements involved. Heat energy from the flame excites electrons to a higher quantum level, and the atoms emit characteristic colors (photons with energies corresponding to the visible spectrum) as they return to lower energy levels [6]
Flame colorants are becoming popular while camping. Scouts [ citation needed ] and other outdoor enthusiasts have placed sections of copper pipe with holes drilled throughout and stuffed with garden hose onto campfires to create a variety of flame colors. An easier method of coloring campfires has been fueled by commercial products. These packages of flame colorants are tossed onto a campfire or into a fireplace to produce effects.
Although these chemicals are very effective at imparting their color into an already existing flame, these substances are not flammable alone. To produce a powder or solid that, when lit, produces a colored flame, the necessary steps are more complex. To get a powder to burn satisfactorily, both a fuel and oxidizer will mostly be needed. Common oxidizers include. [7]
Many of these oxidizers also produce a colored flame by themselves. Some of them - as well as the main colorants - are severely toxic and therefore environmentally damaging.
An explosive is a reactive substance that contains a great amount of potential energy that can produce an explosion if released suddenly, usually accompanied by the production of light, heat, sound, and pressure. An explosive charge is a measured quantity of explosive material, which may either be composed solely of one ingredient or be a mixture containing at least two substances.
An oxidizing agent is a substance in a redox chemical reaction that gains or "accepts"/"receives" an electron from a reducing agent. In other words, an oxidizer is any substance that oxidizes another substance. The oxidation state, which describes the degree of loss of electrons, of the oxidizer decreases while that of the reductant increases; this is expressed by saying that oxidizers "undergo reduction" and "are reduced" while reducers "undergo oxidation" and "are oxidized". Common oxidizing agents are oxygen, hydrogen peroxide, and the halogens.
A flame is the visible, gaseous part of a fire. It is caused by a highly exothermic chemical reaction made in a thin zone. When flames are hot enough to have ionized gaseous components of sufficient density, they are then considered plasma.
Potassium chlorate is a compound containing potassium, chlorine and oxygen, with the molecular formula KClO3. In its pure form, it is a white crystalline substance. After sodium chlorate, it is the second most common chlorate in industrial use. It is a strong oxidizing agent and its most important application is in safety matches. In other applications it is mostly obsolete and has been replaced by safer alternatives in recent decades. It has been used
A Roman candle is a traditional type of firework that ejects one or more stars or exploding shells. Roman candles come in a variety of sizes, from 6 mm (0.24 in) diameter for consumers, up to 8 cm (3.1 in) diameter in professional fireworks displays.
Chlorate is the common name of the ClO−
3 anion, whose chlorine atom is in the +5 oxidation state. The term can also refer to chemical compounds containing this anion, with chlorates being the salts of chloric acid. Other oxyanions of chlorine can be named "chlorate" followed by a Roman numeral in parentheses denoting the oxidation state of chlorine: e.g., the ClO−
4 ion commonly called perchlorate can also be called chlorate(VII).
A perchlorate is a chemical compound containing the perchlorate ion, ClO−4, the conjugate base of perchloric acid. As counterions, there can be metal cations, quaternary ammonium cations or other ions, for example, nitronium cation.
A sparkler is a type of hand-held firework that burns slowly while emitting bright, colored sparks.
Potassium perchlorate is the inorganic salt with the chemical formula KClO4. Like other perchlorates, this salt is a strong oxidizer when the solid is heated at high temperature although it usually reacts very slowly in solution with reducing agents or organic substances. This colorless crystalline solid is a common oxidizer used in fireworks, ammunition percussion caps, explosive primers, and is used variously in propellants, flash compositions, stars, and sparklers. It has been used as a solid rocket propellant, although in that application it has mostly been replaced by the more performant ammonium perchlorate.
Flash powder is a pyrotechnic composition, a mixture of oxidizer and metallic fuel, which burns quickly (deflagrates) and produces a loud noise regardless of confinement. It is widely used in theatrical pyrotechnics and fireworks and was once used for flashes in photography.
A pyrotechnic colorant is a chemical compound which causes a flame to burn with a particular color. These are used to create the colors in pyrotechnic compositions like fireworks and colored fires. The color-producing species are usually created from other chemicals during the reaction. Metal salts are commonly used; elemental metals are used rarely.
A pyrotechnic composition is a substance or mixture of substances designed to produce an effect by heat, light, sound, gas/smoke or a combination of these, as a result of non-detonative self-sustaining exothermic chemical reactions. Pyrotechnic substances do not rely on oxygen from external sources to sustain the reaction.
Barium oxalate is a chemical compound with the chemical formula BaC2O4. It is a barium salt of oxalic acid. It consists of barium cations Ba2+ and oxalate anions C2O2−4. It is a white odorless powder that is sometimes used as a green pyrotechnic colorant generally in specialized pyrotechnic compositions containing magnesium metal powder. Flame color is rich and vivid without additional chlorine donors. Such compositions burn rate is satisfied without commonly used oxidizers as nitrates, chlorates and perchlorates.
Calcium chlorate is the calcium salt of chloric acid, with the chemical formula Ca(ClO3)2. Like other chlorates, it is a strong oxidizer.
Barium chlorate, Ba(ClO3)2, is the barium salt of chloric acid. It is a white crystalline solid, and like all soluble barium compounds, irritant and toxic. It is sometimes used in pyrotechnics to produce a green color. It also finds use in the production of chloric acid.
A flare or decoy flare is an aerial infrared countermeasure used by an aircraft to counter an infrared homing ("heat-seeking") surface-to-air missile or air-to-air missile. Flares are commonly composed of a pyrotechnic composition based on magnesium or another hot-burning metal, with burning temperature equal to or hotter than engine exhaust. The aim is to make the infrared-guided missile seek out the heat signature from the flare rather than the aircraft's engines.
In pyrotechnics, a pyrotechnic initiator is a device containing a pyrotechnic composition used primarily to ignite other, more difficult-to-ignite materials, such as thermites, gas generators, and solid-fuel rockets. The name is often used also for the compositions themselves.
A smoke composition is a pyrotechnic composition designed primarily to generate smoke. Smoke compositions are used as obscurants or for generation of signaling smokes. Some are used as a payload of smoke bombs and smoke grenades.
Alkali metal nitrates are chemical compounds consisting of an alkali metal and the nitrate ion. Only two are of major commercial value, the sodium and potassium salts. They are white, water-soluble salts with melting points ranging from 255 °C to 414 °C on a relatively narrow span of 159 °C
An environmentally friendly red-light flare was a pyrotechnic (firework) flare which used lithium-based formulations that emitted red light. A flare is used for signaling, illumination, or defensive countermeasures in civilian or military applications. It is based on a non-hygroscopic dilithium nitrogen-rich salt that served as an oxidizer and red colorant. The U.S. Army Research Laboratory and the Ludwig Maximilian Institution were credited as the research facilities for developing this product announced in January 2018.