Unit 3 Test Study Guide: Matter and Its Changes

Front

What is the Law of Conservation of Mass?

Back

The Law of Conservation of Mass states that mass is neither created nor destroyed in a chemical reaction. The total mass of the reactants equals the total mass of the products.

Front

How do you balance a chemical equation?

Back

To balance a chemical equation, adjust the coefficients of the reactants and products to ensure that the number of atoms of each element is the same on both sides of the equation.

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What is a reactant in a chemical reaction?

Back

A reactant is a substance that undergoes a change during a chemical reaction, typically found on the left side of a chemical equation.

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What is a product in a chemical reaction?

Back

A product is a substance that is formed as a result of a chemical reaction, typically found on the right side of a chemical equation.

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What happens to the molecules of a substance when it is heated?

Back

When a substance is heated, its molecules gain energy, move faster, and tend to spread apart, leading to an increase in temperature and often a change in state.

Front

What is the significance of coefficients in a balanced equation?

Back

Coefficients indicate the number of molecules or moles of a substance involved in a reaction, ensuring that the equation adheres to the Law of Conservation of Mass.

Front

What is the difference between an element and a compound?

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An element is a pure substance made of only one type of atom, while a compound is a substance formed when two or more different types of atoms bond together.

Front

What is a chemical equation?

Back

A chemical equation is a symbolic representation of a chemical reaction, showing the reactants and products along with their respective quantities.

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What does it mean to say a reaction is exothermic?

Back

An exothermic reaction is a chemical reaction that releases energy, usually in the form of heat, to its surroundings.

Front

What does it mean to say a reaction is endothermic?

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An endothermic reaction is a chemical reaction that absorbs energy from its surroundings, usually in the form of heat.