Chemistry: How Fireworks and crackers works?

Tihar, a beautiful festival, where the weather shows its most elegant beauty   in the form of Autumn. In the same occasion we fire on crackers and fireworks.

Isn't it beautiful when as substance burnt, gives various beautiful colors.

What might be the reason behind this?

Of-course the chemistry.

Background

At first the fireworks was discovered by accident in China. The Chinese accidentally discovered that a mixture of sulphur, charcoal and potassium nitrate burnt quickly with a big flash. Excited by this wonderful sight, they filled the mixture into bamboo shoots and threw them into the fire. The green bamboo shoots exploded making a large sound. And thus, fireworks were born. 

It was only in the 1800s that chemists discovered how to make coloured firecrackers. They identified certain compounds that when used burned to give reds, greens, blues and purples. Today, with advancements in chemistry, new colours of light can be created.

In the olden days it used to be difficult to produce the colour blue. But with the discovery of magnesium-aluminium alloy - Magnalium, this is no longer a problem. We see rich blue fireworks lighting up the sky. Metal chlorides are responsible for the colours that we see in the sky. Strontium for red, barium for green, copper for blue and sodium for yellow.

Firecrackers are different from explosives. They burn by a burning process called deflagration which is completely different from the one in explosives.

What Produces the Colors of Fireworks?

Various chemical elements mixed in with the gunpowder produce a wide variety of colors.

·         Sodium, as found in common salt, emits a strong yellow color when it burns.

·         Copper causes a blue color.

·         Chemical compounds containing the elements lithium and strontium produce a red color.

·         Compounds containing barium burn green.

·         Compounds containing the element calcium burn orange.

To produce a bright white color, the chemical reactions must burn at a very high temperature. Mixing aluminum or magnesium in with the gunpowder will produce a white hot chemical burning reaction.

Just as artists produce colors by mixing primary colors, fireworks displays can also produce colors that are mixtures of other colors. For example mixing the chemicals that produce red and blue colors will produce a purple colored firework display.

To get red, white, and blue fireworks, use lithium or strontium for the red. Use magnesium or aluminum for the white, and use chemicals containing copper for the blue.

What Chemistry and Physics Happens in the Atoms?

The chemical burning reactions in the gunpowder in the fireworks vaporize the gunpowder and the color producing chemicals mixed in with the gunpowder. The hot gas atoms frequently collide with each other in the firework explosion.

These collisions push the electrons to higher energy levels, which are higher orbitals, in the atoms. After a short time the electrons jump back down to the lowest energy level, which scientists call the ground state.

The electrons must release the extra energy, and they release this energy as light. The color of the light depends on the exact amount of energy released when the electron jumps to the ground state.

Physicists and chemists call the specific colors of light emitted when the electrons jump to lower energy levels the emission line spectrum. Each element has its own unique colors or emission line spectrum. Engineers designing fireworks displays select the chemical elements or compounds that have the right emission line spectrum to produce the desired colors for the display.

Understanding the chemistry and physics of fireworks can increase the enjoyment of a fireworks display.

Fireworks and crackers adds Pollution and Health risk

The Crackers and Fireworks helps to suspend many particulate matters in the air. Such suspended particle may remain in the air for many days says the environmentalist, Krity Shrestha. She adds,"Though its a wrong practice against our environments and ourselves but its impossible to stop in the occasions like Tihar"
Extended exposure to particulate matter can lead to coughing, wheezing and even lead to an early death for people with pre-existing conditions like heart or lung disease, according to the Environment Protection Agency.
Already Kathmandu and other major cities of Nepal is suffering from air pollution and the firecrackers adds the pollution.
By-Kabin Maleku