Qns5

Question 5: Thermodynamics (10 + 10 + 10 = 30 marks) a) Hydrogen has been suggested as a fuel of the future. One way to store it is to convert it to a compound that can be heated to release the hydrogen. One such compound is calcium hydride, CaH2. This compound has a heat of formation of -186.2 kJ mol, and the entropy change for the formation reaction is -129.0 J K mol? What is the minimum temperature to which Cahy would have to be heated to produce hydrogen gas at one atmosphere pressure? b) A mass of 35.0 g of H2O(l) at 273 K is dropped into 180.0 g of H2O(l) at 375 K in an insulated container at 1 bar of pressure. Calculate the temperature of the system once equilibrium has been reached. Cs for H20 is 4.18 JK'g! c) Calculate the maximum work that can be gained from the combustion of benzenell) and of H2(g) on a per gram and a per mole basis under standard conditions. Is it apparent from this calculation why fuel cells based on Hz oxidation are under development