Fireworks displays are often associated with celebrations. Some fireworks are rockets that can be fired into the air, producing colorful patterns of bright light. One rocket design involves a cardboard tube, a propellant, and a fuse. A cap on the tube contains metal salts and explosive powder with a second fuse. The propellant consists of a mixture of carbon (C), sulfur (S), and potassium nitrate (KNO3). Potassium nitrate is a potassium ion (K+) bonded to a nitrate ion (NO3–).
A long cardboard tube is filled with the propellant. When a lit fuse ignites the propellant, the propellant releases oxygen, produces flames, and forces gas out the bottom of the rocket. These actions cause the rocket to rise high into the air.
As the rocket reaches its maximum height, a second fuse ignites an explosion that heats and burns the metal salts. This heating and burning of metal salts produces large colorful flashes. Many people enjoy watching these colorful displays against the night sky.
The use of fireworks can be dangerous. Professionals who use fireworks take many safety precautions while setting up and igniting the displays.