The right time to write about fireworks is the New Year holidays.
Today, it is inconceivable for us to have a holiday or celebration without the use of fireworks. Depending on the country, there are different holidays that are most associated with fireworks, but one holiday is unique in this regard in the whole world, and that is the new year.
History of fireworks
There is no reliable information on where and how the fireworks were made. The story is mostly connected with China, where one chef came across the discovery by chance that some ingredients give an interesting color to the flame. Although Chinese legends about the origin of fireworks are the most famous, it is still believed that fireworks most likely originate from the area of India or Arabia.
Before the appearance of the fireworks themselves, it should be said that people made firecrackers. Their existence dates back as far as 1000 years. These were young bamboo stalks filled with gunpowder. They burned them at the beginning of the year, right after the reception, and the role of the explosion was to drive away evil spirits and bring happiness.
In order to have fireworks as we know them today, we need gunpowder, which, unfortunately, was used in the war. The moment someone added balls of various chemicals to the rocket instead of lead balls, the purpose of which was to destroy the enemy, we got the first fireworks intended for fun.
Already in the 15th century, fireworks became an integral part of all celebrations. They were used not only during military victories, but also on occasions such as weddings.
The arrival of gunpowder in Europe is associated with the 13th century and the legendary Marco Polo. Although it was already widely used for military purposes in Asia at the time, Europeans began to use it for that purpose much later. Very soon after the arrival of gunpowder in Europe, workshops and schools for making fireworks began to be established, and they reached their peak during the Renaissance. Even today, many types of fireworks are produced according to recipes from that period.
Chemistry of fireworks
Fireworks consist of a mixture of oxidizing agents, which usually consist of nitrates, chlorates or perchlorates, reducing agents, ie sulfur and carbon, metal salts and binders. A conventional fireworks rocket consists of a cardboard tube 1.5 to 3.5 centimeters in diameter. There is a fuse at the lower end, and after lighting the fuse, the fire causes a gunpowder charge (explosive - oxidizing and reducing agent) which is located in the lower part of the rocket and serves to eject the rocket to the desired height.
Nitrates were first used as oxidizing agents, namely potassium nitrate due to stability and controlled reaction.
2KNO3 → K2O + N2 + 2.5O2
Chlorates give a "more spectacular" reaction due to the higher oxygen content, give faster detonation, but are more unstable than nitrates. Due to their instability, they are more dangerous to handle than nitrates.
2KClO3 → 2KCl + 2O2
However, nowadays perchlorates are more often used due to increased stability and because they are richer in oxygen.
KClO4 → KCl + 2O2
A wooden stick is attached to the barrel filled with explosives, which maintains the flight direction of the rocket. The upper part of the rocket, which contains substances (metal salts) that develop strong light in color, then ignited from the ignited explosive. The appearance of fireworks depends on the way of packing inside the rocket. There is a precisely prescribed distance from the place where the fireworks were fired from the observer, as well as the condition that the wind must not be stronger than 20 km / h.
The colors of fireworks
The colors of fireworks are caused by the burning of metal salts, which have characteristic colors. The atoms of each element absorb energy and emit light of certain colors. With the absorption of energy, the electrons pass from the basic to the higher, excited, energy state. The excited electrons pass from the higher to the lower energy state, and then to the ground state. During these transitions, the electron releases energy (photon) of a specific wavelength - color, which is characteristic of the atom of each chemical element. For example, by burning sodium nitrate, sodium electrons absorb heat energy and go into a higher energy state. This state is not long-lasting, and the excited electrons in the sodium atom soon "fall" to the ground state and release photons of wavelength corresponding to yellow light.
The amount of energy emitted varies from element to element, and each has a characteristic wavelength. Higher energies correspond to shorter wavelengths, whose colors are in the purple-blue region of the visible spectrum. Lower energies correspond to higher wavelengths, ie the orange-red part of the electromagnetic spectrum.