Ch. 7 Test Review

What has to be a reactant in a combustion reaction?

• CO2

• H2O

• O2

• CO

An enzyme is a special kind of catalyst that works to 

• speed up a specific biochemical reaction.
• break down chemical elements.
• slows down a chemical reaction.
• maintains the correct temperature in a reaction.

What is the general form for a synthesis reaction?

• A  +  BX  →  AX  +  B
• A  +  B  →  AB
• AB  →  A  +  B         
• AX + BY  →  AY  +  BX     

In a balanced chemical reaction, the total mass of the products always equals the 

• molar mass of the reactants.
• atomic mass of the reactants.
• total mass of the reactants.
• proportional masses of the reactants.

A chemical equation is balanced by changing or adding

• reactants
• coefficients
• subscripts       
• chemical symbols       

The product of the synthesis reaction between sodium and chlorine gas is 

• copper (II) chloride.
• carbon dioxide.           
• sodium chloride.
• polyethylene.

In an exothermic reaction, energy is transferred from

• the container to the chemicals.
• one reactant to another.
• the surroundings to the reactants.       
• the reactants to the surroundings.

What happens in a chemical reaction?

• Atoms are rearranged.
• Molecules are created.
• Atoms are created.
• Atoms are destroyed.

What kind of reaction is represented by the equation CH₄ + 2O₂ --> CO₂ + 2H₂O?

• synthesis
• combustion
• decomposition
• single displacement

What kind of reaction is represented by the equation 2KI + Pb(NO₃)₂ --> 2KNO₃ + PbI₂?

• double
• single
• decomp
• synthesis