Chapter 4 Chemical Reactions

Chemistry is

• a characteristic of a substance that can be observed without changing the substance into another substance.

• the study of matter and how matter changes.

• anything that has mass and takes up space.

• a rapid reaction between oxygen and a substance called a fuel.

The only sure evidence for a chemical reaction is

• the formation of a gas.

• a color change

• the production of one or more new substances

• changes in properties

A material used to decrease the rate of a chemical reaction is a(n)

• inhibitor

• catalyst

• enzyme

• fuel

CaCO₃ represents a chemical

• symbol

• formula

• subscript

• reaction

Which is the correct chemical equation for the following statement? Sodium reacts with oxygen in a 2 to 1 ratio to produce sodium oxide.

• 4 Na + O₂ = 2 Na₂O

• 2 Na + O_{2 =} 2 NaO

• Na₂O + O_{2 =} 2 NaO

• Na₂ + O_{2 =} Na₂O₂

The principle of conservation of mass is true

• only for reactions that take place in open systems

• only for reactions that take place in closed systems

• for reactions in both open and closed systems

• for no reactions at all

In chemical reactions, what does the principle of conservation of mass mean?

• Matter is not created or destroyed

• The total mass of the reactants is greater than the total mass of the products.

• The total mass of the reactants is less than the total mass of the products.

• Matter is not changed

Chemicals that act as biological catalysts by speeding up reactions in living things are called

• inhibitors

• enzymes

• fuels

• reactants

Which of the following is an example of how to supply activation energy to begin a reaction?

• Cool the reaction flask in an ice bath

• Add a catalyst

• Heat the reaction flask on a hot plate

• Add an inhibitor

A bottle of hydrogen peroxide that eventually turns into a bottle of water and oxygen gas is an example of a

• synthesis reaction.

• decomposition reaction

• replacement reaction

• precipitate reaction