Question

12. The space shuttle uses the combustion of hydrogen with oxygen to power the main rockets. Use the data in the appendix to calculate the standard entropy change, Aso, for the combustion of 1 mole of hydrogen (note: all reactants and products are in the gaseous state). Be sure to provide the balanced equation for the combustion. (10 points). 13. When an ionic solid (like NaCl) dissolves in water the molecules of water separate, surround and disperse the Nat and cr ions. If the solution is saturated the ionic solid can be in a heterogenous equilibrium with dissolved ions (this means that the rate of solvation of the ions is equal to the rate of desolvation as the ions rejoin the crystal surface). Indicate whether the following thermodynamic parameters are positive or negative (10 points) a) As for the solvent molecules that are hydrating a Nation as the ion rejoins the lattice b) AS for a Nation in solution when it is desolvated and rejoins the crystal surface 14. For the following reactions, predict whether they will tend to be spontaneous at high, low, all temperatures, or non-spontaneous at any temperature (10 points) a) An "instant ice-pack" type of reaction where AS > 0, and AH > 0 b) 3A(1) B(8) + C()+D(g), AH < 0 c) 2A(s) B(g) + C(), AH > 0