Problem 91
Consider the reaction $$ 2 \mathrm{ClF}_{3}(g)+2 \mathrm{NH}_{3}(g) \longrightarrow \mathrm{N}_{2}(g)+6 \mathrm{HF}(g)+\mathrm{Cl}_{2}(g)\quad\Delta H^{\circ}=-1196 \mathrm{kJ} $$ Calculate \(\Delta H_{\mathrm{f}}^{\circ}\) for \(\mathrm{ClF}_{3}(g)\)
Problem 92
The standard enthalpy of combustion of ethene gas, \(\mathrm{C}_{2} \mathrm{H}_{4}(g),\) is \(-1411.1 \mathrm{kJ} / \mathrm{mol}\) at 298 \(\mathrm{K}\) . Given the following enthalpies of formation, calculate \(\Delta H_{\mathrm{f}}^{\circ}\) for \(\mathrm{C}_{2} \mathrm{H}_{4}(g) .\) $$ \begin{array}{ll}{\mathrm{CO}_{2}(g)} & {-393.5 \mathrm{kJ} / \mathrm{mol}} \\\ {\mathrm{H}_{2} \mathrm{O}(l)} & {-285.8 \mathrm{kJ} / \mathrm{mol}}\end{array} $$
Problem 97
Some automobiles and buses have been equipped to burn propane \(\left(\mathrm{C}_{3} \mathrm{H}_{8}\right) .\) Compare the amounts of energy that can be obtained per gram of \(\mathrm{C}_{3} \mathrm{H}_{8}(g)\) and per gram of gasoline, assuming that gasoline is pure octane, \(\mathrm{C}_{8} \mathrm{H}_{18}(l) .\) See Example \(6.11 .\) ) Look up the boiling point of propane. What disadvantages are there to using propane instead of gasoline as a fuel?
Problem 98
Acetylene \(\left(\mathrm{C}_{2} \mathrm{H}_{2}\right)\) and butane \(\left(\mathrm{C}_{4} \mathrm{H}_{10}\right)\) are gaseous fuels with enthalpies of combustion of \(-49.9 \mathrm{kJ} / \mathrm{g}\) and \(-49.5 \mathrm{kJ} / \mathrm{g}\) , respectively. Compare the energy available from the combustion of a given volume of acetylene to the combustion energy from the same volume of butane at the same temperature and pressure.
Problem 99
Assume that \(4.19 \times 10^{6} \mathrm{kJ}\) of energy is needed to heat a home. If this energy is derived from the combustion of methane \(\left(\mathrm{CH}_{4}\right),\) what volume of methane, measured at STP, must be burned? \(\left(\Delta H_{\text { combustion }}^{\circ} \text { for } \mathrm{CH}_{4}=-891 \mathrm{kJ} / \mathrm{mol}\right)\)
Problem 100
The complete combustion of acetylene, \(\mathrm{C}_{2} \mathrm{H}_{2}(g),\) produces 1300 . kJ of energy per mole of acetylene consumed. How many grams of acetylene must be burned to produce enough heat to raise the temperature of 1.00 gal water by \(10.0^{\circ} \mathrm{C}\) if the process is 80.0\(\%\) efficient? Assume the density of water is 1.00 \(\mathrm{g} / \mathrm{cm}^{3}\)
Problem 101
It has been determined that the body can generate 5500 \(\mathrm{kJ}\) of energy during one hour of strenuous exercise. Perspiration is the body's mechanism for eliminating this heat. What mass of water would have to be evaporated through perspiration to rid the body of the heat generated during 2 hours of exercise? (The heat of vaporization of water is 40.6 \(\mathrm{kJ} / \mathrm{mol.} )\)
Problem 105
Combustion of table sugar produces \(\mathrm{CO}_{2}(g)\) and \(\mathrm{H}_{2} \mathrm{O}(l) .\) When 1.46 \(\mathrm{g}\) table sugar is combusted in a constant-volume (bomb) calorimeter, 24.00 \(\mathrm{kJ}\) of heat is liberated. a. Assuming that table sugar is pure sucrose, \(\mathrm{C}_{12} \mathrm{H}_{22} \mathrm{O}_{11}(s)\) write the balanced equation for the combustion reaction. b. Calculate \(\Delta E\) in \(\mathrm{kJ} / \mathrm{mol} \mathrm{C}_{12} \mathrm{H}_{22} \mathrm{O}_{11}\) for the combustion reaction of sucrose.
Problem 107
A serving size of six cookies contains 4 g of fat, 20 of carbohydrates, and 2 g of protein. If walking 1.0 mile consumes 170 kJ of energy, how many miles must you walk to burn off enough calories to eat six cookies? Assume the energy content of fats, carbohydrates, and proteins are 8 kcallg, 4 kcallg, and 4 kcallg, respectively.
Problem 109
The enthalpy of neutralization for the reaction of a strong acid with a strong base is \(-56 \mathrm{kJ} / \mathrm{mol}\) water produced. How much energy will be released when 200.0 \(\mathrm{mL}\) of 0.400 \(\mathrm{M} \mathrm{HNO}_{3}\) is mixed with 150.0 \(\mathrm{mL}\) of 0.500 \(\mathrm{M} \mathrm{KOH}\) ?
