# chemistry - decomposition of water(help)

posted by .

Hydrogen is a very appealing fuel, in part because burning it produces only non-polluting water. One of the challenges that researchers face in making hydrogen fuel a reality is how to produce hydrogen economically. Researchers are investigating methods of producing hydrogen indirectly. The following series of equations represent one such method.
3FeCl2(s) + 4H2O(g) → Fe3O4(s) + 6HCl(g) + H2(g) ΔH° = 318 kJ
Fe3O4(s) + 3/2Cl2(g) + 6HCl(g) → 3FeCl3(s) + 3H2O(g) + 12O2(g) ΔH° = −249 kJ
3FeCl3(s) → 3FeCl2(s) + 3/2Cl2(g) ΔH° = 173 kJ
(a) Show that the net result of the three reactions is the decomposition of water to produce hydrogen and oxygen.
(b) Use Hess’s law and the enthalpy changes for the reactions to determine the enthalpy change for the decomposition of one mole of water. Check your answer, using the enthalpy of formation of water.

how do i show the deomcposition of water and for b) how do i start?

• chemistry - decomposition of water(help) -