What is a chemical reaction

A chemical reaction is when a substance (or a few substances) change into another substance. Chemical reactions are chemical transformations.When making beer, yeast turns the sugar into alcohol: that's a chemical reaction. When something iron rusts because of exposure to air, that's a chemical reaction. There are many types of chemical reactions, but they all involve transformations or changes. Water boiling — becoming a gas — is not a chemical reaction, since the steam is still water; the substance didn’t change.

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