1. The problem statement, all variables and given/known data The annual world use of liquid hydrocarbon fuels for transportation purposes currently generates about 10^17 kJ. If we could instead run our transportation system by oxidizing hydrogen gas to gaseous water, we would likely have to obtain the hydrogen by electrolyzing water. Suppose we made and stored enough hydrogen for one year by electrolyzing seawater. By how much would the level of the oceans decrease (in m)? ΔH=-245.12KJ/mol 2. Relevant equations pv=nrt stoichiometry electrolyzing water: 2H2O --> 2H2 + O2 3. The attempt at a solution I have gotten to the point where i have calculated I need 4.17x1015 mol of seawater. I am unsure of how to now calculate the decrease in ocean water.