Atoms in Chemical Reactions TCI lesson 7 & 8 (adjusted)

Chemical reactions happen when:

• The atoms grow until a substance changes state.

• The products break apart into different substances

• The atoms rearrange themselves to form new reactants.

• The bonds between atoms in reactants break and reform to make new substances.

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Which of these best describes electrolysis?

• The name for ALL chemical reactions.

• The division of nitrogen and carbon atoms.

• A reaction that occurs when an electric current passes through water.

• A reaction that occurs any time an electric current is introduced to a rock.

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Electrolysis of water (H₂O) produces which two substances?

• O₁₂ and H₁₂

• N₂ and H₂

• O₂₂ and N₁₁

• O₂ and H₂

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What is a chemical equation?

• A shorthand notation that describes chemical reactions.

• A tool for scientists to solve for the reactants of a product.

• A tool for scientists to keep track of the changes they make to a substance.

• An equation that contains the same elements every time it is written.

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Which of these is NOT true of a chemical equation?

• The reactants are on the left side of the equation.

• The products are on the right side of the equation.

• The two sides of the equation have different types and numbers of atoms.

• There may be more than one reactant and more than one product.

A whole number to the left (Coefficient) of a formula tells:

• Volume of a substance.

• The average number of molecules.

• How many times a substance has undergone a chemical reaction.

• How many molecules of that substance are involved in a reaction.

What happens during a chemical reaction where molecules break apart? They will:

• Dissolve into their original elements.

• Form new groups of atoms that make new substances.

• Completely dissolve into the environment.

• Make a copy with the atoms of another molecule.

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Based on our discussion in class, which of these is a chemical equation that demonstrates the combination (synthesis) atoms of multiple substances?

• 2H₂O -> 2H₂ + O₂

• 2H₂O₂ -> 2H₂O + O₂

• 4Fe + 3O₂ -> 2Fe₂O₃

• Pb(NO₃)2 + 2KI -> PbI₂ + 2KNO₃

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The law of conservation of matter states

• matter cannot be created or destroyed.

• matter that is created can be destroyed.

• matter can be created, but cannot be destroyed.

• matter cannot be created, only destroyed.

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If there are 10 atoms in the reactants prior to chemical reaction, how many atoms will be in

the products?

• 5 atoms

• 10 atoms

• 500 atoms

• 1000 atoms

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