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Chemical Reactions

A chemical reaction is a process where two different substances or elements are mixed together.

They then undergo some sort of chemical change to become a different substance altogether.

Where do chemical reactions occur?

Though you may think that chemical reactions only occur during science experiments in a laboratory setting, they are actually happening all around you every day.


Anytime two or more materials are combined with each other to form a new substance, a chemical reaction has occurred.

Whether it’s wood being burned in a campfire, or a bicycle rusting, chemical reactions are all around us.

How do chemical reactions happen?

Chemical reactions occur when two or more substances are mixed together to form a new material. This change happens because reagents and reactants are mixed together.

While these two phrases might be hard to remember because of their similar names, you should always remember that a reactant is what causes the reaction to occur.

It is also completely consumed during the reaction. Once the reaction is complete, the new substance is known as the product of the reaction.

reaction rate

Are all reactions quick?

Not at all! While some chemical reactions can happen very quickly, like an explosion, some others take a good long time.

An example of an extended chemical reaction would be metal rusting. This doesn’t happen in a quick amount of time, but rather over an extended period.

The rate at which a reaction occurs is known as the reaction rate.

This term is used to describe the entire process, from the time that the reagents and reactants are mixed until they are fully combined into a new product.

How can the reaction rate be altered?

The reaction rate can be altered in a variety of manners. If heat, sunlight, or electricity are added to the reaction, the rate can be increased.


The absence of these forces can also slow down the reaction rated. The amount of reactants added to the reagent can also help to determine the reaction rate, with a greater amount causing a faster reaction.

A third substance can also be used to alter the speed of a chemical reaction.

If this extra substance slows down a reaction, then it is called an inhibitor.

If it speeds up the chemical reaction, then it is known as a catalyst.

Type of Reactions

There are several different kinds of chemical reactions that can occur in both the natural world and a laboratory setting.

catalyst causes reaction

Synthesis Reaction

This type of reaction occurs when two substances are mixed together to make a new substance.

Decomposition Reaction

Unlike a synthesis reaction, where two substances form a new one, a decomposition reaction takes apart a complex substance by separating it into two different substances.


A combustion reaction occurs when a compound is combined with oxygen to form water and carbon dioxide.

Combustion reactions have a quick reaction rate and produce tons of energy in the form of heat.



Displacement reactions occur when one or more compounds take away a substance from another compound.

This can occur as a single displacement, where only one substance is taken away, or as a double displacement, where two substances are swapped.

Photochemical Reaction

This type of reaction is one that involves light and its photons. Photosynthesis is perhaps the best known photochemical reaction.

photosynthesis for kids

Related: Chemical Bonding


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