Chemical Reactions
What is a chemical reaction?
Chemical change
A chemical reaction is a process in which starting substances, called reactants, are changed into new substances, called products.
Signs of a reaction
Common signs include color change, gas production, temperature change, formation of a precipitate, or light being released.
Important caution
A sign does not always prove a reaction by itself. Chemists use evidence from several observations.
Reactants to products
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1
Start with reactants.
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2
Break old chemical bonds.
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3
Form new bonds.
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4
Create products with new properties.
In a chemical reaction, the starting substances are called:
Reactants are the substances you begin with.
Correct answer: Reactants
What are products?
Products are what the reactants become after the reaction.
Correct answer: The new substances formed in a chemical reaction
Which of these can be a sign of a chemical reaction?
Gas production is a common sign that a chemical reaction may have occurred.
Correct answer: Gas being produced
Conservation idea
In a closed system, atoms are rearranged during a reaction, but they are not created or destroyed. This idea is very important in chemistry.