1) [20] The formation of molecular hydrogen at 3000K proceeds through the following elementary reaction: 2H(g)+Ar(g)H2(g)+Ar(g)kf=2.2108mol2L2s1kr=2.2104mol1Ls1 Write the rate law for this process with respect to H2. (a) Calculate the rate of the reverse reaction (rrd[H2(s)]/dt) given [H2(g)]=4.1103molL1 and [Ar(s)]=4.1104molL1; (b) What concentration of Ar is needed to double the reverse reaction rate computed in (a); (c) Calculate the concentration of [H(s)] needed for the forward reaction rate (rfd[H2(s)]dt) to be equal to the reverse reaction rate computed under the process conditions given in (a). 2) [20] The decomposition of dinitrogen pentoxide at low temperatures results in the formation of a brown-colored gas with the chemical formula N2O4, known as dinitrogen tetroxide, a harmful pollutant found in the air together with nitrogen dioxide. On the basis of the chemical equation a student assumed that the reaction would be second order. Using the following data, determine whether or not the student's assumption is correct. 3) [10] A piston-cylinder system is used to store 1000J of work by keeping an ideal gas compressed at a pressure of 4atm. The stored energy is to be released to the surroundings by allowing the piston to expand isothermally at 25C to a lower pressure of 1.5atm. Calculate the amount of gas necessary to carry out the energy transfer if the external pressure is 1atm. 4) [20] Sulfur oxides are pollutants that contribute to the formation of acid rain, as well as particulate pollution. Use the data on the free energy of formation of the oxides of