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 ration to produce sodium oxide.

• 4Na + O_{2 --------}2Na₂O

• 2Na + P₂ -------2NaO

• Na₂O + O_{2 -----} 2NaO

• Na₂ + O₂ -----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.