Unit 6 Chemical Reactions

1) In a chemical reaction

• the number of atoms in the reactants and products must be the same
• the mass of the products is greater than the mass of reactants
• the number of atoms in the reactants and products must change
• energy as heat must be added to the reactions

2) In writing a chemical equation that produces hydrogen gas, the correct representation of hydrogen gas is

• H
• 2H
• H₂
• OH

3) What is the whole number that appears in front of a formula in a chemical equation?

• a subscript
• a superscript
• a ratio
• a coefficient

4) Al(OH)₃ + Cu₂S-->

• AlCu + S(OH)
• Al₂S + OH
• Al + Cu(OH)
• Al₂S + Cu(OH)

5) N₂ + 3H₂ --> 2NH₃ Which of the following is the word equation for the above formula equation

• nitrogen + hydrogen --> nitrogen hydride
• nitrogen + hydrogen --> nitrogen trihydride
• dinitrogen + dihydrogen --> nitrogen trihydride
• none of these

7) According to the law of conservation of mass, the total mass of the reacting substance(s) is

• always more than the total mass off the products
• always less than the total mass of the products
• sometimes more and sometimes less than the total mass of the products
• always equal to the total mass of the product(s)

9) In the word equation, sodium oxide + water --> sodium hydroxide, the formula for sodium hydroxide is represented by

• Na₂(OH)
• Na(OH)
• NaO₂
• Na₂O

11) Which word equation represents the reaction that produces water from hydrogen and oxygen?

• Water is produced from hydrogen and oxygen
• Hydrogen plus oxygen yields water
• H₂ + O₂ --> water
• Water can be separated into hydrogen and oxygen

13) Aluminum + lead (II) nitrate -->

• aluminum nitrate + lead
• aluminum lead + nitrate
• aluminum (II) nitrate + lead
• No reaction

14) Sodium + chlorine -->

• sodium monochloride
• sodium chlorine
• sodium chloride
• sodium monochlorine