Video: Recalling the Meaning of a Reaction Arrow

What is the meaning of the arrow (⟶) in a chemical reaction equation?

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Video Transcript

What is the meaning of the arrow in a chemical reaction equation?

When this arrow is used in a chemical reaction equation, it points away from the reactants and towards the products. The reactants are what you have at the start and the products are what you have at the end. For instance, with the combustion of methane, we start out with methane and oxygen as reactants and end up with carbon dioxide and water as the products. The reactants and the products are not the same. So the arrow indicates the transformation from the reactants to the products.

So in the transformation of 𝑥 to 𝑦, we can say that 𝑥 becomes 𝑦. So one answer to the question of what the meaning of the arrow is in a chemical reaction equation is “becomes.” However, perfectly valid alternate answers are “yields” as in 𝑥 yields 𝑦, “produces” as in 𝑥 produces 𝑦, or “reacts to form” as in 𝑥 reacts to form 𝑦.

The arrow does not mean “is made of” as in 𝑥 is made of 𝑦 because that’s the wrong way around, nor does it mean “is the same as” as in reactants are the same as the products because reactants and products are distinct chemicals.

Remember that this arrow is distinct from the equilibrium arrow, which looks like two fish hooks pointing in opposite directions.

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