Firework Emissions

The colors of fireworks displays are produced by emission from atomic ions as described in Chapter 7. The explosions of fireworks promote electrons to excited states. The energy level scheme of every element is different, so fireworks manufacturers can change colors by incorporating different elements. Sodium ions emit... 

Eor example, street lamps use the emissions from excited sodium atoms, the dazzling colors of a fireworks display come from photons emitted by metal ions in excited states, and the red light in highway flares often comes from excited Sr ions. 

Copper (Cu) is a bright brown-colored metal. When Cu powder or wire is heated in a high-temperature flame, its characteristic blue-colored emission is observed. Thus, Cu particles are commonly used as a component of aerial shells of fireworks. 

Having introduced the theory of emission, we can proceed to the events which occur in a typical titanium fountain (Figure 5.3). This 150g firework will burn for about 25 seconds giving a fountain effect extending some 3 to 4 metres. 

The difficulty in producing a good blue flame stems from several important considerations. Firstly, impurities in the chemicals present in the firework tend to produce yellow flames, which detract from the blue secondly, coloured flames follow similar physico-chemical phenomena but operate in different regions of the spectrum. Consequently the copper salts (that are normally utihsed for the production of blue stars) decompose thermally to produce a variety of emissions that radiate from about 325 to 660 nm i.e. from green, blue and violet to orange-red) simultaneously polluting the pure blue flame which appears in the 400 to 455 nm region. 

The same sources that emit elemental phosphorus to air are also responsible for its emission to water. In its initial states of operation, the ERCO plant in Newfoundland, Canada, which produced white phosphorus, discharged 68-91 kg/day of colloidal white phosphorus into the Long Harbor inlet of Placentia Bay in Newfoundland. Elemental phosphorus was found in both the effluent water and the bottom sediment of Long Harbor (Davidson et al. 1987 EPA 1991). White phosphorus is also expected to be found in the effluents from user industries where it is converted into products such as phosphoric acid and phosphate, detergents, fireworks, insecticide, rat poisons, flotation agents, and red phosphorus (Idler et al. 1981). 

Yellow colors in fireworks are caused by the 589-nm emission of sodium atoms. Red colors come... 

Fireworks above Paris La Grande Arche is in the foreground. Many of the coiors in fireworks are produced from atomic emission red from strontium, orange from caicium, yeiiow from sodium, green from barium, and biue from copper. The sharp iines observed in the emission spectra of atoms can oniy be expiained using the quantum theory of atomic structure. 

How is the light given off by fireworks similar to an element s emission spectrum ... 

A fireworks display is a dramatic illustration of light emission by excited atoms. 

In 1823, Herschel [15] in the Transactions of the Royal Society of Edinburgh published his observations of the colors of flames produced by the introduction of alkaline earth salts. The green color obtained with barium salts is due to BaOH and the reddish color characteristic of strontium salts is caused by SrOH. The red colors of fireworks can also be attributed to emission from SrOH [16]. It was not until the 1950s that modern flame studies [17, 18] identified the molecules that are responsible for the alkaline earth flame colors. In contrast to the alkaline earths, the flame colors of the alkali elements are produced by atomic emission. The formation of molecules such as CaOH and SrOH, in fact, greatly complicates the use of flame absorption and emission for the determination of the concentrations of alkaline earth elements in analytical chemistry. 

Each element has a characteristic line spectrum that can be used to identify the element. Note that line emission spectra can also be obtained by heating a salt of a metal with a flame. For instance, common salt (sodium chloride) provides a strong yellow light to the flame coming from excited sodium, while copper salts emit a blue-green light and lithium salts a red light. The colors of fireworks are due to this phenomenon. 

The brilliant red colors seen in fireworks are due to the emission of light with wavelengths around 650 nm when strontium salts such as Sr(N03)2 and SrCOj are heated. (This can be easily demonstrated in the lab by dissolving one of these salts in methanol that contains a little water and igniting the mixture in an evaporating dish.) Calculate the frequency of red light of wavelength 6.50 X 10 nm. 

Yellow colors in fireworks are due to the 589-nm emission of sodium ions. Red colors come from strontium salts emitting at 606 nm and from 636 to 688 nm. This red color is familiar from highway safety flares. Barium salts give a green color in fireworks, due to a series of emission lines... 

In a typical fireworks device, the heat of the reaction between a strong oxidizing agent, such as KCIO4, and an organic compound excites certain salts, which emit specific colors. Strontium salts have an intense emission at 641 nm, and barium salts have one at 493 nm. (a) What colors do these emissions produce ... 

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