Chapter 03 – Mass Relationships in Chemical Reactions
132. Liquid hexane, C6H14, burns in oxygen gas to yield carbon dioxide and water. What is
the minimum mass of oxygen required for the complete reaction of 10.0 mL of hexane?
(density of hexane = 0.660 g/mL)
133. Liquid heptane, C7H16 , burns in oxygen gas to yield carbon dioxide and water. What
mass of carbon dioxide is produced when 15.0 mL of heptane burns completely? (density of
heptane = 0.6838 g/mL)
Chapter 03 – Mass Relationships in Chemical Reactions
134. Liquid heptane, C7H16, burns in oxygen gas to yield carbon dioxide and water. What
mass of water is produced when 15.0 mL of heptane burns completely? (density of heptane =
0.6838 g/mL)
135. Liquid heptane, C7H16, burns in oxygen gas to yield carbon dioxide and water. What is
the minimum mass of oxygen required for the complete reaction of 25.5 mL of heptane?
(density of heptane = 0.6838 g/mL)
Chapter 03 – Mass Relationships in Chemical Reactions
136.
Nickel has a lower atomic mass than cobalt, even though it has a higher atomic number. One possible explanation is that one
of the average atomic masses was miscalculated. In the case of cobalt, there is only one isotope: 100% 59Co at a mass of
58.9332 amu. For nickel, however, there are five isotopes as given in the table.
Using the data in the table, what is the average atomic mass for nickel?
137. How many moles of aluminum are present in an Al cylinder with a mass of 15 g?
Chapter 03 – Mass Relationships in Chemical Reactions
138. How many moles of iron are present in an iron cylinder that weighs 25 g?
139. Calculate the molar mass, in g/mol, of Al2(SO4)3.
140. Calculate the molar mass, in g/mol, of Fe2(CO3)3.
Chapter 03 – Mass Relationships in Chemical Reactions
141. Calculate the molecular mass, in g/mol, of C6H12O6.
142. How many ICl3 molecules are present in 1.75 kg of ICl3?
143. How many Mg atoms are present in 170 g of Mg?
Chapter 03 – Mass Relationships in Chemical Reactions
144. Calculate the mass of 3.7 moles of Br2.
145. Calculate the volume of 0.15 mole of Br2. The density of Br2 is 3.12 g/mL.
Chapter 03 – Mass Relationships in Chemical Reactions
146.
A chemistry student determined the empirical formula for titanium sulfide (TixSy). To do so, she reacted titanium with excess
sulfur in a crucible, and recorded the following data:
What is the empirical formula of titanium sulfide?
Chapter 03 – Mass Relationships in Chemical Reactions
147.
A chemistry student determined the empirical formula for tungsten oxide (WxOy). To do so, he heated tungsten with oxygen
in a crucible. The data that he recorded are shown below:
What is the empirical formula of tungsten oxide?
148. A compound with a percent composition by mass of 87.5% N and 12.5% H was recently
discovered. What is the empirical formula for this compound?
Chapter 03 – Mass Relationships in Chemical Reactions
149. A compound with a percent composition by mass of 24.61% C, 2.75% H, and 72.64% Cl
has a molar mass of 292.82 g/mol. What is the empirical formula of the compound?
150. A compound with a percent composition by mass of 24.61% C, 2.75% H, and 72.64% Cl
has a molar mass of 292.82 g/mol. What is the molecular formula of the compound?
Chapter 03 – Mass Relationships in Chemical Reactions
151. Select True or False: The definition of a mole is an Avogadro’s number of a specific
152. If 0.66 mole of a substance has a mass of 99 g, what is the molecular mass of the
substance?
Chapter 03 – Mass Relationships in Chemical Reactions
153. Calculate the molecular mass of ethylene glycol, C2H6O2, a compound frequently used as
automobile antifreeze.
154. Calculate the percent composition by mass of sodium in Na2CO3.
155. Calculate the percent composition by mass of carbon in Na2CO3.
Chapter 03 – Mass Relationships in Chemical Reactions
156. Calculate the percent composition by mass of oxygen in Na2CO3.
157. A 0.600 g sample of a compound of arsenic and oxygen was found to contain 0.454 g of
arsenic. What is the empirical formula of the compound?
158. A sample of unknown ore was analyzed and found to contain 12.7% Al, 19.7% N, and
67.6% O. What is the empirical formula of this ore?
Chapter 03 – Mass Relationships in Chemical Reactions
159. Phosgene, a poisonous gas used during WWI, is composed of 12.1% C, 16.2% O, and
71.1% Cl. What is the empirical formula of phosgene?
160. What percent by mass of oxygen is present in carbon monoxide, CO?
Chapter 03 – Mass Relationships in Chemical Reactions
161. Balance the following chemical equation:
NaNO3 → NaNO2 + O2
162. Ammonia is reacted with sulfuric acid to form ammonium sulfate. Write the balanced
reaction (omit state symbols (s), (l), (g), (aq), etc.).
Chapter 03 – Mass Relationships in Chemical Reactions
163. Hydrogen gas is reacted with nitrogen gas to form ammonia gas. Write the balanced
reaction (omit state symbols (s), (l), (g), (aq), etc.).
164. Butane is reacted with oxygen gas to form carbon dioxide and water. Write the balanced
reaction (omit state symbols (s), (l), (g), (aq), etc.).