Problem 104
Methanol, a potential replacement for gasoline as an automotive fuel, can be made from \(\mathrm{H}_{2}\) and \(\mathrm{CO}\) by the reaction $$ \mathrm{CO}(g)+2 \mathrm{H}_{2}(g) \rightleftharpoons \mathrm{CH}_{3} \mathrm{OH}(g) $$ At \(500.0 \mathrm{~K},\) this reaction has \(K_{\mathrm{p}}=6.25 \times 10^{-3}\) . Calculate \(\Delta G_{500}^{\circ}\) for this reaction in units of kilojoules.
Problem 116
Would you expect the value of \(\Delta H_{\mathrm{f}}^{\circ}\) for benzene, \(\mathrm{C}_{6} \mathrm{H}_{6}\) computed from tabulated bond energies, to be very close to the experimentally measured value of \(\Delta H_{\mathrm{f}}^{\circ}\) ? Justify your answer.
Problem 119
If pressure is expressed in atmospheres and volume is expressed in liters, \(P \Delta V\) has units of \(L\) atm (liters \(x\) atmospheres). In Chapter 10 you learned that 1 atm \(=\) \(101,325 \mathrm{~Pa}\), and in Chapter 1 you learned that \(1 \mathrm{~L}=\) \(1 \mathrm{dm}^{3}\). Use this information to determine the number of joules corresponding to \(1 \mathrm{~L}\) atm.
Problem 120
Calculate the work, in joules, done by a gas as it expands at constant temperature from a volume of \(3.00 \mathrm{~L}\) and a pressure of 5.00 atm to a volume of 8.00 L. The external pressure against which the gas expands is \(1.00 \mathrm{~atm} .(1 \mathrm{~atm}=101,325 \mathrm{~Pa})\)
Problem 121
When an ideal gas expands at a constant temperature, \(\Delta E=0\) for the change. Why?
Problem 124
A cylinder fitted with a piston contains \(5.00 \mathrm{~L}\) of a gas at a pressure of \(4.00 \mathrm{~atm} .\) The entire apparatus is contained in a water bath to maintain a constant temperature of \(25^{\circ} \mathrm{C}\). The piston is released and the gas expands until the pressure inside the cylinder equals the atmospheric pressure outside, which is 1 atm. Assume ideal gas behavior and calculate the amount of work done by the gas as it expands at constant temperature.
