But what, exactly, makes up the explosive chemical reactions that create the displays of colors and shapes? Penn Today talked with Eric Schelter , a chemist whose group specializes in the study of metal compounds, to learn more about the chemistry that is involved in fireworks. What can you tell us about the chemical reactions that go into a fireworks display? Traditionally, three reagents, potassium nitrate, carbon, and sulfur, make gunpowder.
Those three reagents react to make solid potassium carbonate, solid potassium sulfate, nitrogen gas, and carbon dioxide gas, so you have solid reagents reacting to make gases. For an explosion, the goal is to generate as much gaseous product in as short of a time as possible. A standard firework has a fuel, oxidizer, and binder. What is the role of each component? The fuel is a source of electrons, something that stores energy, and it will be burned in the course of the explosion.
A chemical reaction, typically combustion, is occurring through reaction of the fuel with an oxidizer. Physical changes are relatively easy to identify. If only the form of a substance changes, you have observed a physical change. C ol o r Changes As in the case of autumn leaves, a change in color is a clue to indicate a chemical change. You have just witnessed a spectacular chemical change if you have seen the leaves change color in the autumn. When you bake a cake, energy is absorbed by the batter as it changes form a runny mix into a cake.
Energy - Absorbed or Released Another sign of a chemical change is the release or gain of energy by an object. Energy can also be released during a chemical change. The fireworks that were mentioned above release energy in a form of light that you can see.
Odor Changes It only takes one experience with a rotten egg to learn that they smell different that fresh eggs. When you smell an odd order in foods such as chicken, pork of mayonnaise, you know that the food has undergone a chemical change. You can use this clue to avoid eating spoiled food and becoming ill. Production of Gases or Solids The formation of a gas is a clue to chemical changes. As wood burns, it turns into a pile of ashes and gases that rise into air.
After the wood is burned, it cannot be restored to its original form as a log. Not easily reversed How do physical and chemical changes differ from each other? How are physical changes different from chemical changes? Do chemical changes involve energy?
What is a physical change? Are physical changes reversible? Question d9d Is the protonolysis reaction of sulfuric acid in aqueous solution an example of chemical change? Fireworks are the result of chemical reactions involving a few key components -- like a fuel source often charcoal-based black powder , an oxidizer compounds like nitrates, chlorates that produce oxygen and a color-producing chemical mixture.
The oxidizer breaks down the chemical bonds in the fuel, releasing energy. Fire either in the form of a fuse or direct flame kick-starts the chemical reaction. The patterns and shapes of fireworks depend on how the stars are arranged inside the shell.
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