Chapter 15

Describe an experiment that would allow you to prove that the system \(3 \mathrm{H}_{2}(\mathrm{g})+\mathrm{N}_{2}(\mathrm{g}) \rightleftharpoons 2$$\mathrm{NH}_{3}(\mathrm{g})\) is a dynamic equilibrium. (Hint: Consider using a stable isotope such as \(^{15} \mathrm{N}\) or \(^{2} \mathrm{H} .\) )

Suppose a tank initially contains \(\mathrm{H}_{2} \mathrm{S}\) at a pressure of 10.00 atm and a temperature of 800 K. When the reaction has come to equilibrium, the partial pressure of \(\mathbf{S}_{2}\) vapor is 0.020 atm. Calculate \(K_{\mathrm{p}}\) $$ 2 \mathrm{H}_{2} \mathrm{S}(\mathrm{g}) \rightleftharpoons 2 \mathrm{H}_{2}(\mathrm{g})+\mathrm{S}_{2}(\mathrm{g}) $$

Pure \(\mathrm{PCl}_{5}\) gas is placed in a 2.00 -L. flask. After heating to \(250^{\circ} \mathrm{C}\) the pressure of \(\mathrm{PCl}_{5}\) is initially 2.000 atm. However, the gas slowly but only partially decomposes to gaseous \(\mathrm{PCl}_{3}\) and \(\mathrm{Cl}_{2}\). When equilibrium is reached, the partial pressure of \(\mathrm{Cl}_{2}\) is 0.814 atm. Calculate \(K_{\mathrm{p}}\) for the decomposition.