Enthalpy and Stoichiometry of Hrxn
71. Consider the following equation for the combustion of acetone (C3H6O), the main ingredient
in nail polish remover.
C3H6O + 4 O2  3 CO2 + 3 H2O
Hrxn = -1790 kJ
If a bottle of nail polish remover contains 155 g of acetone, how much heat would be released by
its complete combustion?
72. The equation for the combustion of CH4 (the main component in natural gas) is shown
below. How much heat is produce by the complete combustion of 237 g of CH4?
CH4 + 2 O2  CO2 + 2 H2O
Hrxn = -802.3 kJ
73. Octane (C8H18) is a component of gasoline that burns according to the following equation:
C8H18 +
25
/2 O2  8 CO2 + 9 H2O
Hrxn = -5074.1 kJ
What is the mass of octane (in g) required to produce 1.55 x 103 kJ of heat?
74. The evaporation of water is endothermic as indicated by the following:
H2O (l)  H2O (g)
Hrxn = +44.01
What minimum mass of water (in g) has to evaporate to absorb 175 kJ f heat?