The significance of Independence Day, also known as The 4th of July, in the United States, is commemorating the Declaration of Independence of the United States on July 4, 1776. The Continental Congress declared the the 13 American colonies were now free and independent states.
On July 2, 1776 was the date that the Independence was approved by Congress, but it was not signed until July 4th and that is why we celebrate Independence day on July 4th instead of July 2nd.
John Adams and Thomas Jefferson were the only signers of the Declaration of Independence who became Presidents of the United States and both died on the same day; July 4th.
Families spend this national holiday by having a barbecue with family and friends, going to parades and then ending the night by going to see fireworks.
We hope that everyone has a fun and safe 4th of July!
Every year millions of people gather to view fireworks on the 4th of July. But how exactly do fireworks emit their colors and pops? Let’s find out below!
There are 2 types of fireworks, the first is called a sparkler and the other is known as a firecracker. Most fireworks that are sold in the United States are of the sparkler variety where they emit showers of colored flames, sparks, noises and other effects. They are often hand-held and generally safer then a firecracker firework!
Firecrackers have been around for hundreds of years. They consist of black powder and ‘stars’ in a tight paper tube with a fuse to light the powder. Stars come in all shapes and sizes, but you can imagine a simple star as something like sparkler compound formed into a ball the size of a pea or a dime. The stars are poured into the tube and then surrounded by black powder. When the fuse burns into the shell, it ignites the bursting charge, causing the shell to explode. The explosion ignites the outside of the stars, which begin to burn with bright showers of sparks. Since the explosion throws the stars in all directions, you get the huge sphere of sparkling light that is so familiar at fireworks displays.
The Chemistry of Fireworks
There are two main mechanisms of color production in fireworks, incandescence and luminescence.
Incandescence is the emission of light caused by high temperature. As a substance heats up it emits colors in different stages starting with infrared, then red, orange, yellow, and white as it becomes increasingly hotter. The temperature of a firework can be controlled and with different components added such as charcoal, can be manipulated to be a desired color at the proper time. Metals, such as aluminum, magnesium, and titanium, burn very brightly and are useful for increasing the temperature of the firework.
Luminescence the emission of light by a substance that has not been heated. To produce luminescence, energy is absorbed by an electron, causing it to become excited, but unstable. When the electron returns to a lower energy state the energy is released in the form of a photon (light). The colors are produced by heating metal salts, such as calcium chloride or sodium nitrate, that emit characteristic colors.
List of colors and elements in Fireworks:
Aluminum – Aluminum is used to produce silver and white flames and sparks. It is a common component of sparklers.
Antimony – Antimony is used to create firework glitter effects.
Barium – Barium is used to create green colors in fireworks, and it can also help stabilize other volatile elements.
Calcium – Calcium is used to deepen firework colors. Calcium salts produce orange fireworks.
Carbon – Carbon is one of the main components of black powder, which is used as a propellant in fireworks. Carbon provides the fuel for a firework.
Chlorine – Chlorine is an important component of many oxidizers in fireworks. Several of the metal salts that produce colors contain chlorine.
Copper – Copper compounds produce blue colors in fireworks.
Iron – Iron is used to produce sparks. The heat of the metal determines the color of the sparks.
Lithium – Lithium is a metal that is used to impart a red color to fireworks. Lithium carbonate, in particular, is a common colorant.
Magnesium – Magnesium burns a very bright white, so it is used to add white sparks or improve the overall brilliance of a firework.
Oxygen – Fireworks include oxidizers, which are substances that produce oxygen in order for burning to occur. The oxidizers are usually nitrates, chlorates, or perchlorates. Sometimes the same substance is used to provide oxygen and color.
Phosphorus – Phosphorus burns spontaneously in air and is also responsible for some glow-in-the-dark effects. It may be a component of a firework’s fuel.
Potassium – Potassium helps to oxidize firework mixtures. Potassium nitrate, potassium chlorate, and potassium perchlorate are all important oxidizers.
Sodium – Sodium imparts a gold or yellow color to fireworks, however, the color may be so bright that it masks less intense colors.
Sulfur – Sulfur is a component of black powder. It is found in a firework’s propellant/fuel.
Strontium – Strontium salts impart a red color to fireworks. Strontium compounds are also important for stabilizing fireworks mixtures.
Titanium – Titanium metal can be burned as powder or flakes to produce silver sparks.
Zinc – Zinc is used to create smoke effects for fireworks and other pyrotechnic devices.
The Sound Fireworks Make
The loud booms that are heard with the firework show is the result of the rapid release of energy in the air which then makes the air expand faster than the speed of sound. This creates a small sonic boom.