CH 4 Test 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.

• 4 Na + O2 —----> 2 Na2O
• 2Na + O2 _______> 2NaO
• Na2O + O2 ----------> 2Na O
• 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 totla mass of the reactans 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