Explain why fireworks explode in colors.

The combustion of chemical components

When a firework is lit, the chemical components inside, such as black powder or other pyrotechnic mixtures, ignite. This exothermic chemical reaction produces a large amount of heat and gas, creating increasing pressure inside the firework. When this pressure becomes too high, the firework casing explodes, scattering the glowing particles in all directions. This explosion is what creates the spectacular effect that we see in the night sky.

Emission of light and colors

When a firework explodes, the heat generated by the combustion of the chemical components causes the emission of light. This light is produced by chemical reactions that release energy in the form of photons. Photons are elementary particles of light that can have different wavelengths.

The color of the light emitted by a firework depends on the chemical elements present in its composition. By adding metal salts to the explosive powder, it is possible to create bright and varied colors. Each metal salt reacts differently when heated, thus producing a specific color.

For example, barium chloride is used to obtain green light, strontium nitrate for red, copper carbonate for blue, and so on. By combining different metal salts, it is possible to create spectacular colorful mixtures that light up the sky during a firework display.

The colors of fireworks can also vary depending on the combustion temperature, atmospheric pressure, and the exact composition of the explosive powder. This diversity of colors and patterns contributes to making fireworks so beautiful and captivating for spectators.

Effect of metal salts

Metal salts are key components of fireworks, as they play an essential role in producing bright colors in the night sky. Each metal salt used in the composition of a firework produces a specific color when it explodes. These metal salts are chosen for their ability to emit a characteristic colored light when heated to high temperatures, as is the case during the combustion of a firework. The colors produced by metal salts depend on the amount of energy released and the electronic structure of the atoms of the metal in question. Some of the most commonly used metal salts in fireworks are barium chloride (BaCl2) for green, copper carbonate (CuCO3) for blue, strontium nitrate (Sr(NO3)2) for red, and sodium chloride (NaCl) for yellow. Each combination of metal salts creates a unique light show in the night sky, offering a wide palette of colors for the visual enjoyment of spectators.

Spectres émis par les feux d'artifice Spectres emitted by fireworks

When a firework explodes, it emits visible light in the form of different colors. This light is composed of various wavelengths corresponding to specific colors. By analyzing this light with a spectroscope, we can obtain what is called an emission spectrum.

The emission spectrum of a firework is characterized by bright peaks at different wavelengths. Each peak corresponds to a specific color emitted by the chemical components of the firework. By observing this spectrum, we can determine which chemical elements are present in the pyrotechnic mixture.

Metal salts added to fireworks are responsible for the emission of specific colors. Each metal salt produces a characteristic color when heated to high temperatures. For example, strontium chloride produces red light, copper chloride produces blue light, and barium chloride produces green light.

By combining different metal salts in the composition of fireworks, it is possible to create a colorful and varied display. The emission spectra of fireworks thus reveal the presence of the different chemical elements used and explain the diversity of colors observed during these pyrotechnic events.