Unit 3 Lesson 6 - Chemical Reactions

Which of these is true of chemical reactions?

• In a chemical reaction, the substances that are combined always form a gas.

• In a chemical reaction, one or more substances undergo a change in state.

• In a chemical reaction, one or more new substances are formed from one or more other substances.

• None of these.

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Which is true about reactants?

• Exist after a reaction.

• The parts of the substances left over after a chemical reaction.

• Change as a result of the reaction.

• Change "states” as a result of the reaction.

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Which is true about a product?

• The substance that exists before the chemical reaction.

• The gas that always forms as a result of the chemical reaction.

• A different substance than the substance from which it came.

• A property used to identify substances in a chemical reaction.

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Acetic acid and sodium bicarbonate combine to form water, sodium acetate, and carbon dioxide. Which are the reactant(s)?

• Acetic acid and sodium bicarbonate.

• Acetic acid and sodium acetate.

• Water, sodium acetate, and carbon dioxide.

• Water, sodium bicarbonate, and carbon dioxide.

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How are scientists able to tell the difference between reactants and products?

• Scientists watch the chemical reaction take place.

• Scientists look for the vivid yellow color in a liquid or solid product.

• Scientists use a table that tells them the products of all possible chemical reactions.

• Scientists compare the properties of the products to the properties of the reactants.

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Which of these is NOT a property that scientists use to identify a substance?

• Density

• Flammability

• Odor

• Surface Area

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Which of these is a chemical property of a substance?

• The ability to change products back into reactants.

• The ability to react with another substance.

• The amount of a new substance formed from a chemical reaction.

• The state change that a substance undergoes as a result of a chemical reaction.

Which of these actions is an example of energy being applied to a chemical reaction?

• Chilling water to make ice.

• Striking a match to produce a flame.

• Applying salt to ice to lower the water’s freezing point.

• Mixing baking soda and vinegar to make a new substance.

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Which of the following is not a condition needed to have a chemical reaction?

• Mixing

• Cooling

• Heating

• Evaporating

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About how long does it usually take for substances to undergo a chemical reaction when they are mixed?

• Immediately

• 5 minutes

• 10 minutes

• They won't react unless additional heat or cold is used.